power valve makes my 440 ping??

If the block was deck'd .040" & heads were milled .025", you'll need to do something with the intake, normally they recammend milling the intake side of th heads, but too late for that, unless you pull the heads, i'm not sure how much will need to come off.

The fuel pressure should come up quik & stay steady IMO, on my duster, i ran a holley blue with 3/8 line & reg., set my pressure at 7 lbs., stayed rock steady through the 1/4 mile every pass, later on i went with 1/2", pressure dropped, re-ajusted it back up, still stayed solid, really didn't need 1/2' line, if your just running a street carter elec. pump, i'll bet its haveing a hard time filling that 1/2 line (that would explain the slow fill & increase on the gauge), there rated about 72 GPH & don't need a reg. or return line) so either get a better pump & reg., or go with a 3/8' line, to comfortably keep a 1/2' line full, i think you'll need a bare min. of a 110 GPH pump, i've had good luck wth the holley blues & blacks, i have a new Procomp 'black" that i paid 55.00 for back about a yr. ago, don't know how good they are, i would sell it to you, but i might be needing it if i ever run Nitrous on my Dart, at least thats the plan.

Another thing, how/where do you have the pump mounted, this is very criticle for pump operation & life, i hope your useing a sump of some sort, i like running fuel cells now, & having the sump in the rear position, then install the elec. pump just behind the outlet mounted on the bumber brase for a straight flow gravity feed too the pump, i never ran a return line, pumps never ran hot neither, heck, they never even got warm.