Hi Adey,
Regarding the much healded proposed upgrade 1397cc unit for your R8, have you considered the later Volvo 340/353 1397cc unit, its has a nice bigger twin choke Weber 32DIR carb and good looking siamesed inlet ports, the cast iron exhaust manifold has a semi 4 branch sweep to it as well, before it becomes a steel pair of tubes, good valve sizes and is rated at 75BHP, its like a big R8S engine, but is a flat topped piston version of the R5G 1397cc Block [ naturally not a crossflow head] It also has the "R8" crossmember 2 cast bosses and integral alternator bolt hole, apart from its massive flywheel, which will swop over to a R5G 180 d clutch system, its a direct swop, with your 1300 bellhousing parts, the Dizzy and fuel pump also as R8 , The R8 waterpump will swap over and the crank pulley.
From memory Salv tuned John Bennet's R8 trails car to be a torquey version to over 90 bhp with a 40DCOE, 4 Branch, and his Cam grind.
Cheers
Dave
p.s Be aware that later 1397cc blocks have course threaded bolts attaching the little support X member, while R8 has a fine thread pitch.