a bowl job will give consistent power increase across the rev range
cam will too, but typically more so in the mid to higher end of the rev range (does a 250 really have a high end of the rev range though
get a late 87 xf efi head (best) and give that a bowl job with maybe a slight port to both exhaust and intake ports. also get it faced.
but yeh i agree they go hand in hand powerwise
either will give a good power gain by themselves but when put together will give an excellent gain