That current chink head, if you move the pushrod hole over yourself, you can port that chink head out to a level close to a W5 head.
My W5’s gave up the ghost on a thin spot and flowed 312 cfm on a 4.125 bore. Some of the top results I have seen have been in the 335/340 area.
The chink head without the pushrod moved have been know to go to 300 cfm. I don’t think you’ll find another 30/40 cfm, but I’m sure you’ll find something!
The W5 was great on paper, poor on execution that wasn’t Chryslers fault but the fault of the casting company in the use of poor aluminum and casting. Chrysler attempted to fix the problem but the damage was already done with the reputation the W5 had earned. The cost of attempting a 3rd fix was deemed too expensive since it would also require a massive add campaign explaining and proving the better castings would be worth the expense. The difficulty of re earning the trust back was considered on top of everything else was thought to be to much.
The cancelled the W5 & marched on with the W7, 8 & 9 series head. Also, being the W2 had a rock solid reputation, the only draw back was its iron and heavy. So they kept the W2 & went on with the 7,8,9 series head.
I always hoped the W5 would come back again. The head still sits in the replacement head category since it really doesn’t take exotic or race only parts for use.
IMO, with the bad rap and huge expense to right the wrong along with the lack of trust due to the crap head production techniques, the introduction of the Edelbrock head sealed the W5’s fate.
The Edelbrock can go 300 cfm. Pittsburghracer produces excellent results with those and the chink heads. Few people fully exploit the heads full potential.
Being done now on most current offerings.
Oh - sarcasm, I missed it!