Apart from getting the sump done, I've actually started building the frame!
I've got a big pile of 1.25" 16swg square section that was intercepted on the way to the metal skip at work. It's old laboratory benching. I have to remove a big bunch of brackets that were used to hold the tops on, but it was FREE!
I spotted some more on Friday.
This chassis is a bit odd. All the outriggers are fairly new, but not a one is in the right place! The outer ends are all approx. 3/8" low and the middle ones are at an angle to the side rails. The front outriggers are the wrong style, they're for the early chassis, although they might actually be stiffer and give a little more clearance for the front wheels.
I'll build the frame to match the factory dimensions and then repair the chassis to match the frame.