In a way, an LX isn't going to be a neat solution. It likely won't run well with power hungry AGP cards, like Voodoo3 3000 or Voodoo5 5500. Once you sacrifice all those upper end options, you are confining yourself to a very limited speed range. You might be better of with a super socket 7 board, where you can use anything from p1 mmx at 133 MHz up to an K6-2/3 at about 500 MHz.
Is it possible to use a mobile Pentium cpu with unlocked multi on a slot1 adapter?
I currently favor the p2-333 & P3 swap solution on a BX board.
To manipulate speed, one can use fsb, multi on the p2, L1, L2 Cache off.
I found that a P3 from 550 to 800 with disabled L1 cache just offers the right speed for wing commander 1.
I am now trying to put together such a machine without the compromises, that my current crate still has. I will try an Asus p3b-f rev 1.04 with two isa slots and a Voodoo5 and a Voodoo1 or Voodoo2 as a junior partner. The speed should be in the range of 133 to 1000 Mhz. The alternative is using a mobile athlon, which can use Multi 3 and up, as well as fsb 100 and up. That would give 300 to 2200 MHz.
With L1 off, you get the performance from slow 286 to 486 by using the multi.
Edit: Drawback on the Athlon is the lack of Isa slots. I have not figured out yet, how I can use my Barton XP-M on a KT133 board, which offers 1xISA.