You need to do a voltage drop test to find your electrical problem. Disable the ignition . Take a volt meter on DC12 volt scale. Put one lead on the positve battery terminal the other on the big post on the starter. Crank the engine and see how much voltate drop you have while cranking. Should...
Pushrods being at a slight angle while not idea are not as much of a problem as you would think. I've worked on a lot of pretty serious BBC and SBC with severe pushrod angles that would scare you that don't have issues.
On another note you CAN run a stock intake on an on center . I did it when...
When my car was running 9.30's with a 3" open down pipe , no exhaust i changed it out for a 3.5" at the track. Two runs with 3" and two with the 3.5" It picked up .05 et and .5 mph in the quarter.
I installed a pistol grip Quarter stick in a GN a couple days ago. It's supposed to fit 200R4 , 4l60e , 4l80e etc. This was on a 4l80. The shifter arm that goes on the transmission is not even close to being useable. I had to weld a piece on it and redrill the hole.