Brian brings up a good point - the light source spills all over the place. I'd have to tent it in some blackwrap, which will be a little ungainly as there still needs to be adequate ventilation.

It's a pretty bright lamp - a projection lamp. I forget how many lumens, but I think it's in the 1k range.

Regarding the lack of an adjustable aperture:
Might a possible work around be altering the time of the exposure? I'd certainly do a test strip first.
Another thought is presenting a physical barrier to the light - a piece of blackwrap with a hole in it, between the light source and the slide? I could try different size holes for different apertures.

Thanks for the thoughts!

Also, any advice on which papers / chemistry to go with would be appreciated. I don't want to dump tons of money into this yet, so any chemicals I buy I'd like to have work for prints as well (assuming I get that far!)