To get more power would it be better to supercharge this motor or build a up a 350?

If you want to stay with a small block build a 383 stroker. Basically start from scratch if you have a 305. I am more into BBC others on here are more familiar with SBC.

I dont want the weight of a BBC.

Get a 350 block and have it bored and stroked to a 383. Most of your parts can be reused. Like the distubutor, alternator, ect... You will need new heads, intake and carb. Or a aftermaket EFI system.

it has efi now can a reuse that ?

If you are serious and really want the engine to run well, then the FIRST upgrade you're going to need is a better breathing aftermarket exhaust system----the stock Merc exhaust system is pretty crude! Stainless Marine exhaust systems would be a great improvement. Also, I think I have seen some USED SBC aftermarket marine exhaust systems in the classifieds. Do a search.

There are a few different choices here for small block application also.

http://www.cpperformance.com/SearchR...er=52&Vendor=3

The engine OEM's seem to agree on the brand of exhaust systems to use.

build a 427 ci small block via world products. That would be awesome in a small outlaw, maybe dangerous, but fun.

I agree.
Build a 400 sb chevy.
stroke this engine,and with good heads and parts, you can easily get 500hp or more!!!!
I have 6 sb400s for sale.
Some 2 bolt some 4 bolt mains.
Will sell for a good price!!!