Recently I revisited the BETA3 pre-release version of Quake which was dated June 11th, 1996 - which is just one month (!) before the actual release of the full "registered" version of the game, as well as listening to some of Romero's Quake 'post-mortems'.

Among other things, BETA3 version still has the full E2M6, which is 1.512.984 bytes in size. The next biggest map in the PAKs is E4M7 with 1.498.800 bytes. But neither of them would fit on 1.44MB floppy drive, which Romero stated several times was their self-imposed size limit "to keep the game at reasonable size".

In the final version E4M7 has a size of 1.495.232, which is like 3KB less than it was in BETA3, and it still would not fit on the 3.5" floppy.

And why "keep game at reasonable size" approach? It's not like they were selling the full version on floppy drives anyway. Maybe BSPs bigger than ~1.44MB were causing other technical problems in the original DOS Quake? Then again, original uncut E2M6 isn't that much bigger. 

Could you maybe provide that full E2M6 somewhere? I know someone merged Romero's cut parts he released separately with the original map and published it on Quaddicted or something, but the original uncut version would be even better ofc, even if it's essentially more or less the exact same thing in the end. 

The only original uncut version by Romero is available in the Beta 3 / Pre-Release version, I'm afraid.

For some reason, ModDB has it for download - https://www.moddb.com/games/quake/downloads/quake-1-prerelease

Unfortunately the sourceports don't run it, since they don't recognize the size/CRC of these PAK files, and BSP map file version is different. Although apparently reQuiem does run it. And there's always option to use DOSBox.

Another thing I wonder is who made the END.BSP in this version, because it looks very Sandy Petersen-ish. 

Alright then. Here are all maps from Q1 beta 3 converted to BSP29 so they can be launched in ports. Enjoy!