ARP main studs will need the sump clearancing... see below.. The engine was weeping oil whilst here, despite only having drizzled some oil over the cams, no oil in the sump in any qty.. anyhows it had a drip on the bell housing face at the rear.. I could'nt leave it as was, as leaks dont get better, only worse... so removed the sump to see this. Beware folks.. It was'nt obvious that the sump was'nt sat flat and flush to the block, hence the gasket sealer did'nt/could'nt seal as it was'nt compressed. Remedy, simply linish off the edge of the sump pan, and marker pen it up and check for witness, and repeat linishing until it clears. something to look out for with your builds.