I am horrified to discover that the 8F build had been stalled for over 7 months...... Must get my finger out.
I now have a functioning chassis. Clearances are very tight.
Pinch points are the usual crosshead/front coupling rod boss but there are others:
Connecting rod - second wheel coupling rod boss
Connecting rod - expansion link.
We pack this kit with threaded crankpin bushes as it would be impossible to build without.
I found it necessary to thin the connecting rod big end boss so that the connecting rod misses the expansion link and thin the back of the connecting rod so that it misses the coupling rod boss.
But it works!