50 is better than 0
. It is a good start. I probably started with 50 when I was trying to be convinced to put some ballast in. I run 140 lbs. now and have had as much as 190 with the bigger 460 BBC I run now. But 140 seems to be about right for me. Put 50 in and see what it does.
8" rim is ok with those tires. I always ran mine on 8" rims and run my 9" hoosier radial slicks on 8" as well. I'm sure a 10" rim would be better. Just wanted to make sure you didn't have them on a 7". The worst thing is too wide a tire on too narrow a rim.
Good luck.