I have an old FSM for my 89 that's made of paper. I'm pretty sure it has that data in there. I'll probably forget to look when I get home...I think 16mm and thread ?. Now in my senility I remember I have a can full of them, I'll try to check...
I think thats a good decesion on the oil pump. Hope you get a good one. Check it out close for flecks of metal on egdes where casted. Frank R had a problem with one there.
And a very good decesion on the HB. They are a soft metal and I don't think it takes much damage from abuse and general waer to make one unbalanced. I tried to buy 2 but they both came in cracked(NAPA locally. )They were Chinese cast and metal was full of bubbles and they crcked apart in shipment , Beware).

dave h.
'89 Raider V6 5spd;Aisin Hubs;; Gen2 LS: frt. brakes, rear coils;U.C.arms;R.trailing arms;idler arm; rear LSD axle w.disc brakes ;2 battery system for Dog's fan; relocated ECU; custom bumpers;J.Baker receiver;Conferr roofrack; t-bar crank.