I plan on swapping in an 350 based on an L31 shortblock and know it doesn't come with an oilpan and was wondering if I could reuse my oiplan and (flexpate?) that hooks to tranny?

 

The issue is 1-piece vs. 2-piece rear main seal for both the pan and flex plate. I'm not completely sure about the L31, but that should be a one-piece. Since no one else responded, I'll take a guess that your '92 305 pieces will work.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, Hooker headers & y-pipe, 3" Catco cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, 3.08 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

Thanks, the L31 shortblock is a 93-up Vortec 350 shortblock. It's a nice piece.