valve stem height - need some help

Here's the latest update, with many thoughts. Let's start at the beginning. My primary goal with these heads is weight reduction. When I find it, this 383 will go in a 67-69 Dart or an equivalent car. Saving weight up front is important, as I'm more of a street handling guy than a balls-out straight-line guy. I am not trying to build a giant killer, just a fun and spunky street car for my own pleasure. The fact that these heads should be quite a performance improvement over the existing 906 heads is icing on the cake.

I fully respect the wide variety of opinions posted so far, and I get it that intelligent and informed folks can look at the same information and come to completely different conclusions.

That said, the first question is - does the difference in valve stem heights make any difference for the kind of build I'm after? To use round numbers, the exhaust valve stems are about .040" shorter than the intake valves. My first thought when working on this build is to go hydraulic cam, partly to re-use the existing valve train parts. I understand a solid cam is generally a better deal, but again I'm not trying to squeeze out the final tenth of available ET in the quarter mile.

The root cause of this stuff is the EX valves are shorter than the IN valves by about .040. I measured each valve for OAL along with the measurement from the top of the retainer groove to the top of the valve stem. By the time you do the math, it all works out right. Basically, the EX valves are .040 short in comparison with the IN valves. If this is No Bid Deal, I can clean up the heads, put them back together, and call it a day. If it is a big deal, then I will call SpeedMaster and see what they say about using two different valve lengths.

Other than the stem length issue, the heads look quite good. One of them is from 2018, the other is 2015. The newer head is clearly better machined, but it won't take long with a 6" burr to fix all the casting flash issues and have some really nice heads.