I've been pondering the same question myself. I've been piecing together parts for a trad style track roadster for a few years now, a '26 T roadster on A rails that will run a 261 Chev or 270 GMC. I hauled a reasonable 270 out of a deuce-and-a-half a few months ago but it too has the small port head. I beleive the 270H heads are scarce because they were pulled from production after a few years due to a problem with cracking, so it is likely that if you did find one it would need a ton of work anyway. You could fit a 302 head, but then you'll need custom pistons as the 270 pistons from Patrick's don't work with a 302 head. The speed manuals of the day stated that the ports on the big port heads were considered too large for a street application due to a loss of air speed at low rpm, and recommended porting out a small port head instead. I have a manual by Frank McGurk that recommends enlarging the intake side ports to 1 7/16", enlarging intake valve ports to accomodate a 1 15/16" intake valve, and enlarging exhaust valve ports to take a 1.6" valve, but it probably wouldn't flow much better than the stock head on my 261. I guess it depends on how fast you want to go. In a light car that should be enough to beat a few flatheads. It would be good to hear from someone who has actually used a small port head like this. I hope this helps.
