Hello Mate, as ive said you will need to pocket your pistons anyway , even a std engine always touches valves when you buzz it or miss a gear , if you want any sort of power and reliabiltiy take engine to whichever engineer ( and your cheque book ) and let them get on with it .
Dont buy mis matched components and then expect the builder to make a good job of it , a good engineer will spec the comp ratio and machine the pistons all at once for you . Sounds like you'll use a T34 for about 400bhp , if thats true dont lower the comp as you'll have poor drive off boost .