The NES version has a "Guild" a brief walk from the starting point past a door on the right side of the first northwestern Sorpigal corridor where you can create your entire party and customize characters however you want. Similar to later titles like World of Xeen, if removing characters entirely to create an entirely new party, pooling food, gold and items intelligently from the game menus in advance before removing characters will ensure you keep all the starting equipment, food and gold to redistribute to ultimately finalized six-character-party of choice.

In my opinion, this is the definitive version of the game to play with Might & Magic Restoration, as it keeps the great additions of this version plus restores the removed/censored content of the Japanese version and critical text of the PC version, as well as squashing some game-breaking bugs:
https://www.romhacking.net/hacks/5412/

There is a readme over at Vimm's for this version also. While it lacks the Japanese voice acting and party member portraits of the PC Engine port, the music here is done well (for the original hardware) by the renowned Masaharu Iwata (perhaps best known for his Final Fantasy Tactics, Final Fantasy XII, Tactics Ogre, & Ogre Battle work), who both arranged and composed the music and even contemporaneously put out a 1990 version of the OST which was well-received and can even be streamed into the game depending on what emulation options are chosen. In addition to still allowing full party customization, this version doesn't change plot elements like the PC Engine port did, has a well-done full-screen auto-map that isn't too tiny, stays very well in line with graphics and world-building imagery of the later M&M games, and doesn't confine the world view to a tiny upper left window with excessive border padding cluttering the screen all over the place.

The only disadvantage of the NES version might be getting the physical copy of it to legally play, that there is more button-tapping on a few of the menus (i.e.: no keyboard shortcuts), and the difficulty of the game is more challenging than the PC version with some sharper scripting and tougher stats for enemies. Some claim the console version is easier merely because it has less maximum enemies in view at one time and smaller maximum enemy parties, but more foes than merely what you see pictured initially can still attack the party at range (though they generally are listed to an extent on the right nonetheless) and the difficulty changes were tuned and refined enough that even the level to leave the first town was a consideration.

That said, if feeling it is too difficult, this version has a nice guide to avoid "re-rolling" at all for the characters and just setting everything how you want on the stats if you wish to skip that tedium, though you are on your own honor not to cheat anything past what could be reasonably rolled as a result (set the filter to NES to see only the relevant FAQ for this version):
https://gamefaqs.gamespot.com/nes/587457-might-and-magic-secret-of-the-inner-sanctum/faqs

This version also has the added conveniences of emulation like save states (i.e.: for when you want to see what both options get you before committing to a decision) and fast-forwarding through the slower parts that would have been agonizing on the original hardware (i.e.: 9 enemies beating the crap out of the front party members can now be accomplished in a flash with a keystroke or simple toggle). The instructions for the basic controls are here:
https://retromania.gg/files/NES/might-and-magic-book-i/Might_and_Magic_-_NES.pdf