Interesting. That bullet probably isn't the best choice....but: The big groove is a lube groove. Did it come with lube in it, or is it just plain lead? If there is no lube, then we'll get back to that in a minute.
If you are very careful you might be able to crimp the mouth of the case right at the bottom of the ogive (the rounded nose of the bullet) at the top of the top of the driving band. That is the wide band above the lube groove. You can probably bend the mouth of the case over a little just past the top of the band, but you'll likely ruin a few before you get the hang of it. You'd probably be better off to seek a different bullet that has a groove for crimping. Anyway, you are correct that headspace will suffer if you crimp into the lube groove, as your cartridge's overall length (OAL) will probably be too long to chamber as the nose of the bullet will jam up against the rear of the rifling in the bore.
Back to the lube, if there is none, and you wish to continue with this bullet, you'll have to apply some to the groove. At your entry level of reloading equipment there are two ways to go that I can think of:
(1) You can stand the bullets upright in a shallow pan in which you've melted some lube. Let it harden and then cut the bullets out of the lube with a tool of close to the same diameter as the bullet diameter. A 45-70 cartridge case would probably work, or any case with a .45 diameter body. You'd want to cut off the neck (if it has one) and the base leaving a .45 size tube, so that you can put it over a bullet and cut it out of the lube, then put it over another and cut it out, another, etc. until they pass through the tube and start coming out in your hand. This is usually referred to a "the cookie cutter method" of lubing. Lee Precision used to make lube sticks specifically for this application, a mixture of wax and alox, but I don't know if they're still available. Most lube sticks as used in lube machines might work, or you could brew up your own lube.
(2) Another way you could lube them is to do each bullet manually with some grease from a can and something like a matchstick for an applicator. At this point, in this area we're pushing the limit of my knowledge, as I just experimented with making up some loads with this method this winter, and have not as yet tried them out. There once was a fellow who posted on the forum, and I believe he was from Argentina (but was never certain as he wouldn't specifically say) and he had to improvise reloading methods, tools, and supplies due to shortages where he lived. He advocated the use of white lithium grease as a bullet lube and said that he got excellent results. Anyway, I found myself in possession of a batch of approx. 215 gr. .454 diameter un-lubed bullets from an unknown mold, so I decided to experiment and loaded them into .45 ACP cases for use in a 1917 revolver. Apply the grease carefully, and wipe off any that gets onto the base of the bullet so as not to contaminate the powder charge. As you seat the bullet, any excess on the sides will kind of hydraulic its way out of the mouth and can be wiped off with a rag. I can not, at this time, say how well it will work as far as long term storage, preventing leading, accuracy, etc., but will get around to shooting them this summer. I've attached some photos to illustrate what I'm talking about.
To re-cap, my opinion is that you should probably look around until you find some pre-lubed cast bullets that have a crimping groove, and just store your present bullets away until you have some more advanced equipment. But, you might be able to produce some acceptable ammo by proceeding as outlined above, cookie cutter lubing or smear lubing, and careful crimping just above the top of the upper driving band. It will be labor intensive and time consuming, but perhaps that works for you.
Attachment 238707Attachment 238708Attachment 238709Attachment 238710
Click to enlarge.
Some afterthoughts: If you go to the top of the page and click on the link to Lee, then click on bullet casting, then on
handgun molds, take a look at molds # 452-200-RF and #452-228-1R for .45 ACP. They have a definite crimping groove and might be very suitable for your needs. Of course, you'll have to buy a mold, and then you'll become hooked on casting your own. Lastly, a third method of lubrication you might try that had slipped my mind -- Lee Tumble Lube. Just about the easiest way possible to lube boolits, just pour some in a container, swish your boolits around in the lube until they're coated, then put them on some newspaper to dry. They're ugly, but it works well. Best wishes on your project.
DG