Engine Swap to 79 -84 350 sbc pulley / water pump / harmonic balancer question

[72ArizonaBurb]

I bought a long block from a 79 - 85 model Chevy from a local guy and started to re-assmble it the other day. I ordered a water pump for a 72 Chevy and when I tried to install it doesn't fit because of clearance with the timing chain cover. So I returned it and got one for that model and now I am concerned about all my pulleys lining up.

Here is my question. Can I take a timing cover off an older model and then return to the original pulleys or will I need to change all my pulleys to later models?

Also will the timing marks on the harmonic balance be in the wrong place if I use a harmonic balancer from the 79 - 85 model? Can I put the balancer from a 72 SBC on and everthing work out okay?

Thanks in advance for your help.