You could save your self a lot of hassle by just buying an H.O. Alt.
http://mechman.com/store/product_inf...roducts_id/374
I'm sure that will be plenty for your plans.
I would also recommend an XS Power battery. 1 S3400 would work great.
I personally run a Mechman 300 amp alt and 7 D3400's. Soon to be 2 Mechman 300's.
Edit- Running anything much bigger than that 150 amp on a v-belt is going slip like crazy. If you want bigger invest in a serpentine.