I too am not quite sure what you're looking for. But I assume that you're looking for a way to neatly take all of those conductors from a panel change that are too short to make it into a new panel - but dont want to have 4-5 4Sq's as a junction from old to new?
Well.... How much money you got? And how neat would you like it to be?
Super cheap: Use existing as a J-bx, and nipple to new.
Cheap: 4Sq's and remove and replace in same location with new.
Still cheap, but expediant: 14X14 NEMA 1 or 3 j-box at existing location - nipple to new.
No longer cheap - but neat: Same as above, but with terminal blocks.
Not cheap at all - but really neat: Same as above but with DIN rail terminal blocks.
The word "Cheap" can not be used: Extend/repull all wiring to new panel...
Mark Heller "Well - I oughta....." -Jackie Gleason
You can group all the grounds on a busbar and bring them in on a single conductor (I would use a 250-66 size but that is probably overkill). I also remember a question about whether it was OK to group the neutrals but I don't remember the answer.
If you are extending NM wiring, those big Carlon J boxes do a pretty good job and you don't need a set of punches on the truck to make the holes. I know that may be a foreign concept to commercial electricians but a guy who only does 1&2 family doesn't really punch metal that often. You can drill the Carlon box with a $2 holesaw.