833 23 vs.18 on 440/6

Hello Guys,
I'm sure this has been hashed out before BUT!!! My '69 Swinger was an original. 340/4speed, When I bought it a while back the guy before me installed a OEM BB K frame
From DIRECT CONNECTOIN installed era correct 440/727 on the floor with Hurst His/Her
Dual Gate shifter era correct.now I would like to put the 4speed back( pedal still there). Will an
ERA correct 833 out of a 70 Swinger work 23 spline from a 340? It's 23 3/16 long,WILL IT TAKE
THE PUNISHMENT FROM THE 440??? (550 hp) Also the 10 1/2" Flywheel? I know the bells are
Different. ANY AND ALL HELP APPRECIATED, JUST GETTING BACK IN THE GAME AFTER ALL THESE YEARS AT 57!!
MITCH