I'd change the cam... I hate the B-cam or any of the ford cams for that matter. Comp XE cams appear to be the way to go. If you have 370 FWHP expect to see 320 - 330 at the wheels give or take depending on the variables. X heads definetly flow enough to make good power just nothing insane. I wouldnt hold your breathe without major port and bowl work to get them much past 400 hp. But I'm gonna guess that probably isnt your goal or is it?
My official guess o metre 320 whp and 300 wtrq (but I have been known to guess high in the past)
My $.02 on this. that crate engine was tested with a Edelbrock or Holly Carb...I beive a 750 that's how they got the 345 flywheel HP out of it. With an EFI intake that combo won't make more than 250-260RWHP...NO WAY! The engine is a good engine capable of 12's with the right gear. The heads are actaully really good but could use some slight porting. Check out my sig...I have the same heads but ported and polished and my car is a 5 speed now and I made 291RWHP and 322RWTQ untuned...so I really don't see how 280RWHP is even possible with those heads and an E-cam...Hope this helps.
Sorry I didn't get those posted for you, I was really busy in the garage this weekend.
A carb throws a spin on the entire dyno as you will almost always see more HP over an outof the box EFI set-up. 370FWHP = @ 304RWHP still a little more then I see the Ford Crate Motor making with a Cobra/GT-40 arrangement, not saying it can't be done but it is rare.
I had a custom cam very aggressive NA AFM grind, worked Holley alum heads, Holley Intake, 75mm TB, 80mm MAF 30# inj, 1.635" long tubes, 2.5" exhaust, all tuned through my Speedbrain ECU and it yeilded about 340RWHP...lot of work, lot of tuning....