Claton, First buy a copy of "Hot VW's " magazine at the drug store.
Next look for a rebuildable "core" dualport engine built after '68
expect to pay $100.00..... you can build one up for about 500- 800
bucks, (there's a little machine work to do if you want to use big bore
cylinders.) Expect 55 honest horsepower if you build an 1835 version.
The VW aftermarket parts sources are enormous! Have fun!
.........Marvin www.flysquirrel.net