um..when #1 is at its most..up...thats TDC. Without the head on it doesnt matter. If you paint TDC one on the crank..rotate it 360*...its still TDC. No matter what. Rotate it backwards 360*...still TDC. It wont matter any till the head and timing belt is on.
Best way to get EXACT TDC is to use a dial indicator on the crown of the #1 piston and rotate it till its at its most extended. Then rotate clockwise till its a 0 deck height..then rotate it counter clockwise to the highest number, continue counter clockwise back to 0 deck height. Half the total of both readings.
Much like finding out how many feeler gauges to put in each side of your cam lock plate. Everyone does that right?