need help trying find trans for vx cale 5.7 litre or can u recon n quick shift mine 2nd gears missing

Hey im looking to put a bigger v8 in my vl it jas a 4:11 diff wiyh spool and stage 2 shift kit in trimatic gearbox. It has a new 253 but want more ponys should I put a 350 or 355 or 383 its going to be in summer nats again as I bought this vl from a guy who went into the nationals with it. . . Or will a stroked 253 to a 310 supercharged do the job also the car will be reg on the road. What you think I should do need some tips. And can you buy bolt in turn key motors?