360 w/J heads-need help deciding

Hey guys-I have a 73 Dart Swinger with a worn out 318. I dont have the expertise or skills to rebuild my motor myself, so I have been looking for a drop in solution. I would like to buy a crate motor but just too much $$$ right now.Im seriously considering buying this motor from a guy. Please look over the build combo information below and let me know your thoughts or if there are any red flags with this combination. The heads are J heads that he is picking up from machine shop this week. He claims the machinist bill is $1400. He said I can come look at it in its current state and he wil finish reassembling.

"1981 model 5.9L 360. fresh rebuild all pistons cleaned up and cylinders were honed. The motor is a short block right now but I have everything needed to reassemble it. comes with 69' model J heads that have 2.02 valves (which are brand new) motor comes with a gasket set, milidon oil pan, new distributor, .509/294 dur mopar purple bump stick, edelbrock RPM performer intake, mopar performance valve covers, new oil pump, new main and rod bearings and piston rings already installed.

The heads are milled and have a good sized port job already done. I have them at the machine shop right now getting the valve job finished:.

He claims this set up should net around 400-500 HP.
Any comments would be appreciated.
Thanks,
Todd