1997 Chevy Blazer compresion check help

I just had the heads on this 97 GMC Jimmy 4X4, Auto,4.3 vortex GM V6 machined, at this point the intake and exhaust manifolds are on and I would like to run a compression check before I put it all the way back together, but I have no power when I connect the battery, the battery shows 12.35 volts, on the positive side there is a thinner wire that connects with an eyelet that evidently needs to connect some where to have power to the starter. I can trace the negative to cable to the block and has continuity, the positive cable traces down to the starter. Also I have no lights or dash lights when I turn the key any ideas