I read here that the Indy Mids don't have the best grind clearance but I look at the forged version of them.
50.5mm height sounds pretty good to me. My question is, can I put I regular kingpin in them and shorten it a bit with a angle grinder and low top bushings?
I don't feel like dealing with inverted kingpins that come loose over time.
It is not the inverted kingpin that comes loose, so much as it is the inverted nut arrangement that you cannot remove without messing up the whole baseplate, but from trying out other inverted kingpins, some do tend to work well in the Mid baseplate and allow for a lot more clearance, if the kingpin has more threads, you can definitely take it down lower.
What might be an easier option is putting the Mid hanger on a normal forged baseplate and using an angle grinder to take the kingpin down as much as is needed, which I have done for a whole lot of trucks and it works well and gives a much better clearance anyway, even on the Mid hanger.