I believe D.S.S. has 3V stoker long blocks with ported heads and custom camshaft grinds. Check them out I purchased a block from them years ago, priced right, built great and performed as they said it would.
Wow... I don't want to know what shipping would be on a long-block overseas... What are you're power level goals that will require a beefier motor? I'm just thinking, cost savings, and since you have to install everything yourself, you might just be better off going with a blower kit... Unless you have some crazy power goals, in which case, more power to you lol.