So, during one autoslalom practice session this happened:
https://goo.gl/photos/TWpUBQe9572Lt36b8
https://goo.gl/photos/hjucJu7Tj7o4fFu6A
https://goo.gl/photos/6EtPPaCMVzfiyJFv8
Oil was everywhere, even on the sidewalls of front tyres and on the back arches.
The oil filter came loose, eventually the oil pressure spat out the gasket and covered the whole engine bay in oil, and the engine seized within 20 seconds.
https://goo.gl/photos/PauafvotyCaMt9MR7
I got trailered home, and found an ST170 engine form 300€ the next day
https://goo.gl/photos/JQf2QYwkHvmPvVCq5
The ST170 manifold won't fit in my chassis, as the plenum extends behind the back of the engine, where the chassis and battery are on my car. The Silvertop Mondeo manifold won't fit perfectly because ST170's intake ports are ~5 mm higher (Silvertop gasket on ST head):
https://goo.gl/photos/basU9UcvLwsoL2xSA
I did some browsing around, looks like to get the most of the engine I will have to control the VCT from Megasquirt. In order to do that I'll need to get the MS3X extension board from the States. I will need an extra VR input for the cam sensor and a PWM output for the VCT solenoid. Beyond that, it should be just a question of tuning.
The ST manifold and plenum are two plastic pieces connected with rubber joiners. They can be separated and the manifold is a popular start for a bike throttle project.
Besides all that, the sump needs shortening and the alternator/water pump belt needs to be sorted out (identical to a normal blacktop, it seems).
Since it did not look like a quick install, I looked for a Silvertop engine at the breakers, and got a nice Mondeo 2.0 lump for just 90€. I put it in in a couple of evenings. Back on the road in a little over a week!
https://goo.gl/photos/sCYXKmXRRF8XLhtv8