[Big-Foot]

Ed,

I could say that the odds are in your favor that you will have sufficient clearance at low RPM. However, as things wear and get to shaking at higher RPM, you may end up with just a touch of valve float and potentially some piston rock since your engine is not exactly fresh as a daisy. The primary thing you need to be concerned with is the piston chasing down the exhaust valve as it is moving to the top of the exhaust stroke. You want .100" clearance during this process to take care of any incidental valve float as well as to compensate for growth of the piston (yep they grow a fair amount and no two are the same) and rod stretch in the higher RPMs.
The only way you will know - for sure - is to pop one of the heads and do a "clay" test on one of the pistons. Yeah, I am fully aware of how much work that entails - so pick the easy side to do it...

If you knew of someone else who had the identical configuration and they had done the clay test, you could probably use their data.

Otherwise - Unless you are willing to pop one of the heads, I would say that the gamble is just not worth it..