I have some input that seems to fit here - but then I ALWAYS have input, don't I?

My Dad and I raced PV544's back in the late 1960's through the mid 1970's. Our engines were a large part of our success. We always used the B20, and shaved the heads as well as decked the blocks. Compression ended up in the 14:1 range.

In fact we blew the porcelain center out of more than one spark plug!

In addition to a hot cam, we added much larger valves and used the Weber carburetor. As I recall, VW valves were perfect for the setup, but I don't recall the specifics.

The problem we had to overcome was the high compression continually blowing out the head gasket. In the end we machined a groove into the top of the block around each cylinder and installed a copper O-ring along under the head gasket. We never lost a head gasket after that, even though we had to carry an extra set of spark plugs!

While a 14:1 compression ratio is far too high to use with the crappy commercial gasoline we get today, the O-ring would be a good idea if you start having problems with head gaskets. If I were blueprinting a B20 I'd have it done as part of the build.

Also, the Carter H6SU's were better for performance, but took too much
'fiddling' to keep them in tune. Thus the swap to the single Weber carb.