as said youve gotta use the f20/f18 mount on the side of the f28 drilling out and tapping 3 exisiting holes. its such a bad solution tho change gear, pull off hard and it will snap clean in half, slam everything down and destroy your inner cv joint at the same time. Theres a guy on mig doing custom rear mounts which use the orginal f28 rear mount position @ £85 quid. i just put an order in for one should be alot better.
as for the linage you cant use either f20 or f28 linkages, youve gotta make a hybrid of the two, linkages are in three parts, gearbox end, middle and bulkhead end all held together with circlips. IIRC (maybe wrong as i havent done it for 2 years or so) i used f20 gearbox end and middle and used the bulkhead end from the f28