Unless you have some of real early 350 Poncho pistong they should be of a slight dish anyway. Also you can have a slight dish machined into Pontiac pistons as the machined chambers are very noncondusive to spark know as there are no hot spots like on rough cast heads.
I would have figured any cam under .550 lift(most Pontiac heads top out unported in the .520-.530 range) and don't get greedy with duration. As in N/A use 260-280 duration 110 or 112 centerline and in .500-.525 lift range. Also testing with 1.65 rockers gives better idea on valve clearances.
And composite gaskets with closed chamber and negative ie down in the hole should put it around 9.8ish if it's higher order up some .060 deadsoft copper gaskets, spray with copper coat and torque with head studs. Pontiacs don't deck walk like other engines.
They're FTs. Virtually every Poncho ever made was FT. There's no "we'll adjust the compression with dishes" like a Chevy mill. The closed chamber heads will hit with the valve near instantly coming off the seat, so they would need quite a bit of clearance work. If I had some sacrificial slugs I'd be more willing to test it.
I'm actually really inclined to run the 43s be They also certainly paid money for a valve job to be done on these heads, at least the intakes are freshly cut with the bowls opened up. Perfect for me to get the carbides and sanding drums out and work over some. cause they have screw in rocker studs and see what they do. Compression would be in a territory between jack and shit though.
Cam wise, I have a 214/224 110LSA in the old engine, not sure what's in the "new" one. I'll see if I can get the ID marks off of it, but I may just swap mine in if it's not trashed with the old engine. I think it's plausible it's over cammed for the compression, but the old one ran okay N/A and knocked down a best of 17MPG highway on the qjet with 3.23s and no OD.
I popped the 43s off the "rebuilt" engine today, broke them down and looked at the porting work on the one head. The intakes are done conservatively, the exhaust appears opened a bit much but I'll live with that I think. I need to finish up the porting work, the heads have a fresh valve job too so that's nice. I need to get an engine stand, put the engine I got on it and check it out. I suspect that I'll find more RTV debauchery done by the bubba that built it.