Ha! I think there's a reasonable risk of me getting it not square/level if I try that.
I don't know what happened to the old one! I was the lucky recipient of a very kind donation of a box of bits and I've been gradually excavating them out of the caked on rust and grime. I even managed to get the motor back to life, although I do now need to strip it down and try to replace the bearings. Anyway, various things were missing - the table being the most major, but also the little post that holds the lid up, the locking nuts for the depth stop, the spring cover and so on.
To be honest I've no idea whether the ply thing will work - it may have too much flex to stay level under pressure, but we'll see!
I've got all the other bits broadly clean, but now need to get the diesel off before painting...and expecting a ton of criticism for using a brush, but I don't have a sprayer.