Dave,
sounds like you're on track. I don't think the timing is too picky for starting on these - if you do it as described I think you'll be ok. Any pops at all and you're in the ballpark. None, you're probably timed on the sympathetic cylinder (ie, six vs. one).
A low battery/slow cranking speed and low compression from sitting and frozen rings can prevent starting. Sounds like you know enough to tell if it's cranking fast enough. If needed, you can jump a 12-volt battery to your six to get started. Be sure everything electrical except ign. is OFF, and only leave the jumper cables on the six volt. battery as long as necessary to get it running, then take them off. A lot easier if you have help!
Also, are you confident the exhaust isn't plugged up and that it can breathe?
Just some thoughts . . .
-Michael
