engine building isnt hard but you have to be anal about it. you have to make sure everything is spotless, everything is triple checked for torque etc. the actual process is easy though, can have it done in a few hours (unless you have to reseat valves! they are a shit on a 4e head!) you just CANNOT get lazy with it, you have to make sure its all done properly. as for your 5e question. yes, 5e block, crank and rods with fte pistons work. if youre serious about doing it, send me a pm and ill give you a few tips, im the wins with 5e conversions