I'm getting there...

I went to S&S Preparations and got an airbox, air filter, washer bottle and some tubing for the 1850. I fitted the parts and put a nut on the other exhaust thread and the car runs a lot quieter (still blowing a bit) and there's no smoke from the exhaust. Once I'd lowered the front end back on the ground (it was on axle stands) I was able to drive the car. Once I've sorted out the exhaust properly, replaced the inner headlight and got the welding done (found another small hole at the back of the OS chassis rail. Ideally it needs replacing) it should be ready for the dreaded MoT.