Hi guys I'm building a 250 crossflow for my xf s-Pac I need some advice on what to do to get some decent power so far I've had the head shaved a mild porting job stiffer valve springs a mild hydraulic cam with hydraulic anti pump up lifters extractors with a 2.5" exhaust with a free flowing muffler and a 2 barrel 350 Holley I'm not sure if I should go with a 500 Holley or just stay with the 350 it is a 5 speed manual and I've got a heavy duty clutch with a lightend flywheel with a balanced harmonic balancer this is my first Ford build so I'm sceptical about putting a el crank and 200 rods in it

Any help/advice would be greatly appreciated cheers Josh