Birthday AD&D game

As part of my birthday celebrations I'm running N1 Against The Cult Of The Reptile God [spoilers] for a group of about 8 players on Saturday from 12pm-6pm (ish). I've not run 1st edition AD&D in a very long time and want to use some of the improvements that have come along with later editions. On top of that 8 players can be slow, even in 1st ed, so I've streamlined the combat even further, particularly around initiative and player order. Effectively what happens now is the following:-

• Optional surprise d6 roll based on class, with Thieves, Monks and Assassins being surprised on a 6+, Fighters, Paladins, Rangers, Clerics and Druids on a 5+ and Wizards and Illusionists being surprised on a 4+. Monsters such as Bugbears add to this roll. 
• The initial roll is made by the player who's character is unsurprised and has the highest dexterity rolls d6 and adds their reaction adjustment, as do all the monsters in similar fashion. Which ever team scores highest goes before the whole of the other team.
• Players take it in turns to do their move around the table. The starting player is the whoever is sitting closest to the DM's left or right, alternating left to right between each combat.

Other rules changes include positive Armour Class values, so that they are target values (e.g. Chainmail is normally AC 5, but is now AC 15 and therefore the base to-hit is 15+), spell mastery so that spellcasters can substitute their memorized spell with the spell they have chosen to master. (Often Cure Light Wounds or Magic Missile).

I've worked up a single page rules explanation cheat sheet with many of these based on the character sheet PDF, which can be downloaded here.