Thanks for the shutter speed info on box cameras, JBrunner, that helps a lot. Sounds like I need to be at 100 iso to give me some leeway +-2 stops. My local lab does Kodak better than some of the exotics (I don't develop my own yet). So, I think I'll give T-Max 100 a try on the first roll.
No way am I going to use slide film on the first roll. I tried that once with some Fuji Provia 400 with a camera that had a working light meter, but it was off by 2 stops (unbeknownst to me). Got nothing back but clear slides.