Me too, I think the GHQ Leopard 1A4 is 'close enough' to a C1 in 1/285th. I'm thinking of being crazy and doing the Royal Canadian Dragoons 1-1.
There's a Canadian model maker that makes a set to turn a 1/35 Leopard 1A3 into a C1, but it's really expensive. The Meng 1A3/A4 is so close, but the detail differences make it easier to use a new turret. I'm afraid that after I save up and drop the $200 USD it'd take, then Meng or someone will just release a C1 in plastic.
One thing I was thinking is what the RCD would have in the Twilight War, would they get the C2, or C2 MEXAS upgrades, or still have C1s? Takom make a nice 1/35 C2 that I'm thinking of for my skirmish game.