Some of the older engines (tractors mainly) iv'e seen have a mark on the bottom pulley of the engine. If that is not the case, you may consult a Chrysler manual at your local parts store.
there should be timing marks on the crankshaft damper .use a very bright light to find the marks,if it's a typical 225 you will have to do some heavy duty cleaning to find them.
when you set the timing be careful,I blew up the 225 in our swather because the timing was off 5 degrees and it overheated.the older chryslers seem to be very picky about timing. Shadow
I set it by turning the distributor on EVERY gear. there were 13 gears so there were thirteen possible positions. When I go to the right one, she took off like a house a fire. The engine sounds absolutely beautiful.....sounds like a stock car on a race track with that unmistakeable Chrysler engine deep throated rumble. Thanks guys Faber