Sorry, I don't know this off-hand. I'm away at the moment but when I get home I can scan the detail of a Z Car magazine article of a similar build done by a friend of its previous owner at the same time. See if there any clues.The Toyota R20 pistons look worth a look, are they 30mm ish compression height?
Maybe this is a stupid question but are the valve positions and angles the same on all l series heads?