Radiator Needed

Going along with Wedgie...

You could buy a 273 style water pump from your local parts store. The old style timing covers had a bracket for the timing marks that used the bottom two bolts of the water pump to attach. You could use one of those and put a mark on the damper to mark TDC. I always fill in the line in the damper with white touch up paint or white out to make it more visible anyway. Then you could use your old radiator if it is still good.

Don't forget the fan shroud. It is needed to pull the air through the radiator properly with a good fan. the fan should be half in and half out of the shroud as a general rule of thumb for proper cooling.

If you are willing to buy a new radiator, the later water pump is aluminum vs cast iron for the old one. Then buy a radiator with the proper outlet locations and use the 340 set up.

You can make it work either way. It is your choice of whichever you prefer.