I would go closed deck but just convert the crank to centre thrust not the block, much cheaper.

I also agree re 14mm studs(hassle), just get the top of the range ARP studs, so much easier and just as good.

I would go to Danny at Performance Mods or Niel for block prep. If u know what your doing most of it is in the prep, clearances, deck height of piston, compression ratio, actually degreeing the cams in correctly etc etc.

Just my thoughts after building a few EJ20 that have held together under some extreme conditions.