Hey man,
I'd say go for it! Those heads are plenty enough to make a 331 rock n roll, and in countless chassis dyno runs I have seen VERY LITTLE difference in similiarly built 347s vs 331s. Are those heads the highest flowing model on earth?...of course not. However, they DO flow enough to support over 500hp, which in reality is probably more stress than you want on a factory block anyway; unless I miss my guess. And with that good intake you've already got, a well spec'd 331 with the right amount of static comp. to support whatever cam timing your wants and needs dictate, can and will make enough power to actually hurt itself...which should be considered "plenty" in any case, no? DSS makes a really nice, lightweight 3cc flat top for the TFS heads that hangs on a 5.315" rod, which will put you really close to 10.5:1, assuming a .030 overbore and just a clean-up cut on those heads, with a 0 deck. I'd say close your intake around 64-66 degrees ABDC, and stick with a 112 lobe sep, putting you in the 272-276 advertised duration range, with lift around .550 on both sides (provided the heads are sprung right), and maybe something like a 6-8 degree split. It'd be easy to tune, SHOULD get you in the 425-450hp range with gobs of torque, all before 6000rpm, which means it should outlive us all with proper maintenance, and it would run on 87 octane dog water as long as you don't get it hot. Trick Flow made 350hp and 370ft/lbs with those heads and a li'l baby cam with substantially less lift than the heads will support, on a 9.5:1 306, right?....well, if anyone disagrees that another point of compression, a little more cam, and 30 more cubes through a quarter inch more stroke should easily net a guy another 75+ ponies and the torque to go with it, I'm all ears. Either way, I look forward to updates on your build, and hope it all goes smooth and you have a ball doin' it, bud!