[Commander]

You can't just look at the cost of the heads themselves.

If you go SOHC, you'd need not only the heads themselves, but the front cover (and backing plate), specially modified water pump, special pistons, the chains, and the two cams. And the cams are ground unlike any 'normal' cams and so, are NOT cheap themselves.

So basically, you're looking at $15,000-$20,000 MINIMUM for a SOHC engine vs way way way way less for a pushrod FE (and $30,000-$40,000++ cammers are probably more common if you get any builder(s) involved).