SB engine rebuilding got ya! School is Open!

I need some schooling! These are great tips but I have some more specific questions? Background first...74 GoldDuster 360LA...I needed a timing chain for sure and a water pump....decided to yank the motor to inspect, clean, re-seal everything after a rally in which we pushed it past it's limits. We ran it hot for a good while knowingly......don't kill me. I also decided I'd replace oil pump while I had the motor out.

Tear down/Inspection- to my surprise almost everything looked marvelous! Valves looked new, cylinders look spotless, cyl walls look nice and barely see crosshatch still, oil was clean with absolutely nothing on the pickup strainer. Also found out it was a '75 HD block with '75 HD shotpeened crank with aftermarket cylinders (never ran numbers on block when bought used) Water pump bearing not good, timing chain slack as I've ever seen one!

Following steps taken- have Jheads got them cleaned, 3 angle valve job, seals the works, replaced 2 valves...but forgot to ask how much heads were milled? Replaced oil pump with melling standard pump. Cleaned everything block and all mating surfaces, installed comp cams dbl roller timing chain set.

Main questions- if I want to replace lifters and pushrods do I need to use an adjustable pushrod length checker or get same length rods?
Should I degree the cam if I didn't replace it (I don't fully understand the process) even if timing marks line up?
Should I have the engine deck surface milled or checked? On a tight budget but do not want to miss crucial issues
Should I use cometic gaskets or similar high end MLS gaskets? Fel pro is horrible in my experience. Victor reinz ok usually but new technology has me wondering?
Are their any tips or advice you can offer at this point?

BTW- I'm new here, and thank anyone for acceptance and advice!