SNH,
Go ahead and build the 305/335. The biggest problem you will have is heads. Don't use the 305 heads use good aftermarket (World Products makes nice 305 heads) heads and build it like any other sb chevy. You will have a "square" (3.75" x 3.75") motor and should have a lot of torque. I am going tp build one sometimes in the future with a TPI. This a link to Powerhouse who builds a kit for this application. I don't think I would try to put together an assembly myself because, as has been pointed out, it would be cost prohibitive.
Just my thoughts and good luck.
Jim
Also, I think you would only have to change pistons and rebalance to build a 383.

http://www.enginekits.com/ek/RetailCatalog.pdf#search='powerhouse%20335%20stroker'