Under Supplement No. 3, Triumph Spitfire 1500, Section 1 - Engine Modifications:
2. Crankshaft and Connecting Rods
Use stock factory main bearings with .0025" clearance and "Clevite 77' MGB rod bearings, Part #Clevite CB792P, in .010" undersize. File the outside edge of the locating tang on the bearings to fit bearings to the rods. Even though the bearings are quite a bit wider than stock, they only need chamfering to fit. Grind the crankshaft to 1.8665" (about .009") to get the recommended .002" clearance. Prepared this way, bearing life will be indefinite. Since there is no harmonic crankshaft damper available, use a small crankshaft pulley made up out of aluminum. (See drawing for details.) The connecting rods are run virtually stock except for the removal of casting marks and balancing. If shot peening is available, have the rods shot peened. Replace the rod bolts with 3/8" socktes head screws, Grade 8.
That's off pg. 42-43. I checked dimensions twice for typos, all good. There is an acompanying diagram that dimensions the replacemnet front pulley. If you're going there, I could fax that when you need it.
Hope this helps.