So I was driving down the road and I heard sounds like my water pump was going out and then my timing belt snapped. So I replace the water pump and I’m about to put the new belts on and I noticed the rear balance drive pulley isn’t freely spinning. So to further investigate I removed the pulley and it spins freely it just when bolted back to the engine it will not rotate. So I guess I’m just looking to be pointed in the right direction from here

 

When a belt snaps on these engines it often causes serious damage. bent valves, broken parts inside. At the very least the head is damaged in some way, which is why it won't rotate. I'll offer an opinion, there is more than one way to deal with it.

1 - you can take the head off to see the damage (or have your mechanic do it). Likelihood of damage to the top part of the engine, meaning the head, is 99%. If this is the case, you could have them repair it. My guess is $1000 for the repair.

2- Because I would presume that is the issue, my suggestion is to go to the salvage yard and get a junkyard head and simply swap that on instead. Cost of part is probably $100 (and you need a new head gasket). Labor is whether you do it (free? and tools) or maybe $300-400 for the shop?

The bottom of the engine (pistons, etc) should be fine, but when you pull the head you can inspect it.