Rontanamo

Hi all, new to the forum and over the past few days been on the site alot seeking answers. I am very familiar with small block chevy's and everything about them, I recently bought a 1978 Datsun 200 SX dirt track race car. The engine has issues and I am working through them, but at some point I will more than likely need the expertise I have seen and read on here. First off, when I went to purchase the car, it sounded sick and I noticed the carb was not flowing properly and it was popping through the carb not to mention the electric fuel pump died while we were running the car, I got the price down so low I couldn't resist taking a chance on the car thinking it was a fuel related issue.....or not. Last night I changed the carb from a holley 350 to a holley 500 from the shelf and it was off and running, but it would still occasionally popping back through the carb, after rotating the distributor fully clockwise, no more popping, however the car wouldn't get past 3k RPM. Tonight I popped the valve cover to check the timing chain and tensioner and everything look good, but I noticed a rocker was off the valve, then I noticed a second one off as well. I put them both back on and adjusted the valve lash to the specs I had seen listed everywhere, put the valve cover back on, fired it up, same issue with the popping back through the carb until I rotated the distributor fully clockwise, then it smoked like there were 20 guys vaping non stop in the engine, after a few minutes all the oil and whatnot burned off and it ran very well, I gave it a few revs and it sounded very good actually, I was about to rev up past 5k, but this engine (assuming was actually built as advertised) is a L20 but it is a 2.4 and I assume (assume being the operative word), that the engine should be capable of more RPM's though I didn't feel comfortable with the timing and what not so I stopped, not to mention the oil leaks I was discovering while doing this. I know nothing about these engines and I am picking it up as fast as I can. I need to verify TDC is what is marked on the crank pulley, if it is, the distributor is not pointing to #1, it is almost 180 or more actually, some of those details are blurry as I was in a mad rush to fix the obvious. If any of the info I have posted is incorrect let me know please, lot of work to do!