[Grady Clay]

Andy,

Yes, you are correct. You should test assemble the engine and measure the clearances first. Only then can you make an informed decision. With close clearances you should test assemble a second time to confirm what the final clearances are.
All this effort can prevent a disaster. It is not a good situation to find out that at high revs the pistons touch the heads.

Are you going to install twin plugs also? How much boost?

Best,
Grady