Slick 60's

Hello All,
I've replaced the 240 in my 65' with a 300 long block. When trying to initially start it, it tries to fire the first couple of turns then won't do anything. My question is how do I know the timing is near correct? Should I have my wife turn it over while I turn the distributor in either direction?

Thanks for any info.

what i would do is pull #1 plug turn over motor with ratchet via crank pulley to tdc on timing mark and stick a long screw driver carefully in plug hole and if piston is at top youll know then take valve cover off see if you have play in rockers on #1 that way you know motor is at tdc then have your rotor turned to #1 plug wire on cap and install wires according to firing order. always has worked for me