What other differences are there between series 1 and 2?
Being a manual there's not the major difference L98 vs L77 as autos face comparing Series II to L76, apart from L98 has LS2 valley plate vs L77 deactivated VLOM and deac lifters. Good news in that regard is while VE L77 gets revised Delphi lifter that may get noisey they do not fail like the old VLOM sand Eaton combo on the L76.
I'd definitely choose Series II (L77) because finally sorted ECU less OS screw ups / compatibility for tuning, redesigned throttle body and intake manifold, PCV / oil consumption, ethanol flex fuel compatibility, better fuel management (FPCM firmware), high pressure fuel pump, revised a/c unit and HVAC operation, a/c belt tensioner, water pump, bumper / headlights, diff mount, IQ unit, and lot of other stuff in the detail.
Main thing is pre-Series II autos have problems largely rectified with L77 update, so for resale whether manual or auto is tarred with same brush.
L98 has no better cam or sturdier valvetrain than L77, the main advantage would be saving a couple of hundred dollars if you were to swap cams - L98 can swap without lifting heads.