I have dropped rubber test dummies from a B-25, but never jumped it. ... tears in my eyes. You could cram a few para-troopers into the bomb-bay or a half-dozen into the waist-gunners' position. However, the waist-gunners' position suffers from the same problem as Whitley: ringing-the-bell!
Douglas AD-1 (especially the wider versions) had a large enough fuselage to haul a few paratroopers, but the side door is too small to carry anything more than pistols and grenades. Stock Grumman Trackers have the same tiny side door.
During the 1950s, USMC Recon types jumped Grumman Traders and jet Skyknights. C-2 Greyhound is also approved for jumping. The C-2's rear ramp is great for dropping rubber boats or LAPESing light vehicles, but you do not need a ramp to drop static-line para-troopers. By the time you cramed 22 para-troopers' rucksacks, rifles and snowshoes into a C-2, they would need to take turns breathing!
Hah!
Hah!
OV-10 Bronco can carry 3 or 4 lightly-armed para-troopers behind the cockpit.
At various times, there were mock-ups of two-man pods hung under Harriers and Apaches for sales campaigns. No army admits to buying those crew pods. When the Brits had to evacuate casualties (in Afghanistan) they sat them on stub wings and wrapped seat-belts around them. Israelis brag about similar lash-ups.
I was skydiving in the Mojave desert (winter 1994) when some US Army Rangers flew down from Fort Lewis, Washington to do the first free-fall jumps from CV-22 Osprey prototypes at Edwards AFB. FF is only relevant for inserting small teams. Far easier to land the team together, than try to collect them after jumping. That is the only advantage of CV-22, as airliners and other military transports have more range and can carry more paratroopers.
Enough about hardware ... To get the maximum number of jumpers out on one pass, you are better to put two streams simultaneously out two or more side doors (both side doors on C-130 or all 4 side doors on IL-76).
Tactically, para-troopers are best limited to recon, sabotage or forward artillery spotters who land a few miles inland a day or three before the main landing party. I doubt if one aircraft carrier could carry enough para-troopers to make a serious dent in any coastal defenses, but a handful of naval gunnery officers could make life miserable for defenders long enough to land the main invasion force by boat or helicopter.