Hi Jim,
Can you take a closeup of how the fuel racks are connected? Because I couldn't see it in the photos posted... would be interesting!
Regarding the decompression - I'd expect the starter to be able to pull the engine through full compression. My 6/1 has a mangled together ST head, with a flex plate off, erm, something, and a Ford 12v starter motor on it, and with a good 12v battery, it has no problem with compression. I don't have the solenoid on mine, so I have to do any fuel rack closing/decompression by hand; that's more to do with laziness than anything else, I've just never got around to sorting it out properly....
COVs - these were never fitted to the 8/1 engines, they always (IIRC!) had a "blanking plug" installed. Presumably, by then, Lister were able to confidently run the engines at full power on the higher compression; or maybe the plugs give a half-way house between low and high. On the older 3/1, 5/1 and so on, the higher compression was required to start, but once running, the engine was less stressed on the lower compression (and still gave the power). Of course, that would presumably mean that your S-o-M set would automatically start, then you'd have to dash out to the engine shed (in the cold wet and dark - this is England after all!), spin the C-o-V to low compression; then, when going to bed, you'd presumably have to repeat the process to ensure the engine was on high compression, ready to start in the morning! More likely, I bet every S-o-M lighting plant spent the bulk of its life on high compression....