1989 Mazda 929 Head Gasket Replacement

Long diatribe so there's a donation:-)
A timing belt idler pulley bolt sheared off and made a pretty total mess out of the engine. The bolt that sheared was in the right (passenger) side head. So thinking I could easy-out the broken piece and helicoil fix the hole I went at it. Screwed up royally and drilled into the water jacket. Fast forward. I've removed both heads, a non-trivial exerciise, there's not a damn thing wrong valve-wise. When the belt breaks on this (SOHC) all valves slam shut. I've purchased a replacement head for the damaged side. I've also purchased a valve grind gasket set and new head bolts. I own the factory shop manual too.
My concern center around installing the heads. It is getting cold, low 40's to mid 50's. Will I encounter improper installation with everything cold? The head install calls for oiling the bolts and head facing, torque the bolts in order to 14 lbs. Then, in order, turn 90 degrees, then another 90 degrees. The old head on the left looks good, measured flat enough, the engine deck seems OK. Is there anything I should be extra careful about? Will the colder weather affect the install? Should I do anything with the head gaskets, spray with oil or just be sure all is clean and dry before assembly? This is the most important part of the job and I do not want to screw it up. Advice and hints greatly appreciated. Any other advice with re-assembling this motor is highly desired too. Thanks Much