403 Olds in a 77 Buick Electa overheating

So I bit the bullet and decided to rip the engine almost all the way down. I'm leaving the crank and pistons alone. I did not notice any excessive play on the crank to rod bearings. I had a hell of a time getting the crank timing gear off! The chain was replaced but the person who did it used a pipe wrench or something similar on the crank! (Picture attached) I had to use some plumbers emery cloth to smooth it out enough to get the new gear on. I just hope it's smooth enough to get the new balancer on. I'm guessing that using a little RTV or Indian head on the balancer where it contacts the shaft won't hurt since the crank was scarred.
I got a new Melling high volume oil pump, drive shaft and pick up. Does anyone know how to attach the pick up screen to the pump? It looks like it just pushes in but I don't think that's right.
I also bought a new Tough One loaded distributor and water pump. Next I will install the new oil pump but as I said, I'm a little confused about how to attach the pick up screen.
I'm going a little slow with this build. I've never done an engine with less than a short block. Health issues are a problem too. I can only do so much each day.
I'm definitely taking lots of pictures and documenting everything I'm doing. I can brag later if everything works. If this fails, I can cry about how much time and money was spent.
I just happened to notice something today. While BSing with my neighbor standing over the engine, I noticed the oil slinger may be missing. Does anyone know if this 403 is supposed to have an oil slinger in front of the timing gear? The chassis service manual shows a slinger but the chapter covers the Olds 403 and Olds 350. I'm not sure if they are on in the same. I can say the 403 I'm slowly fixing came out of a '77 TA. I'm just not sure about the slinger. I ran into another problem, after installing the new oil pump and pick up, the oil pan will not go back on. The drain bolt is hitting the oil pump body. Looks like trying to save $ on this build is not going to happen. Looks like I need to either put the OEM pump in or get a deep oil pan.

Sorry if I seem to run on, I'm copying from other forums with the same questions.

 

...and mine as well. An Olds engine isn't all that bad to do a chain on. If your problem started right after they did the chain, then the smart money would bet that the chain repair is the problem. The harmonic balancer could be off, but if I ran the shop that did the chain, I would have sold you a new balancer.