It'll be just fine if there is room on the strut housing. Did that years ago when I wanted to put 12" coilovers on the front of an RX-7 with zero preload. I carefully cut the welds with a saw, ground the tube smooth, slipped the perches down to the height where I wanted them, zap zap and they lasted more or less forever. The only PITA part of it was finding the right height, because I wanted zero preload, so I had to keep assembling/disassembling the struts. (Wet cartridges!)
Re: valve face griding. Eh, you just did what a machine shop would do, the only difference is a machine shop has a better method of fixturing
And by "better" I mean there's something to chuck the valve stem into as you grind it on the side of a grinding wheel.
