A lot depends on how much you mill the heads and what type. also do you 0 deck the piston or leave them .030 to 0 down. advancing or retarding the cam from manufacturesrs segested intake ceterline also gives more or less room. Edelbrocks seem to end up with less valve clearence than other heads???

That said i ran an ultradyne 263/271 @ .050 .597/.620 lift cam 108 lobe separation advanced from 106 straight up position to 104 with 0 deck and .060 off 906 heads with 2.14/1.81 valves with no problem .038 gasket but it was tight!!!
ended up deepening the valve notches and milling the heads .105 (made closed chambers)