There are actually three different types of Midway Space Invader games. There is the original "Space Invaders", then there is "Space Invaders Deluxe" (which displays "Space Invaders Part II" on the screen because of some licensing issues with Taito, waaay long ago) and there is a more obscure one called "Space Invaders II", in which two players play head-to-head at the same time (it's a cocktail-only game). So Space Invaders Part II IS NOT THE SAME as Space Invaders II!
The Midway versions of Space Invaders, Space Invaders Deluxe and Space Invaders II were all made as a two board set. The smaller of the two boards is officially called the "game logic board", but it is usually called the "daughterboard" or "sound board". It plugs into a connector on the larger board (known as the motherboard). There is a pair of aluminum brackets that hold the two boards together.
The daughterboard for SI is different than the daughterboard for SI Deluxe and SI II. The daughterboard for SI Deluxe and SI II can be used to play "regular" Space Invaders software, but the opposite is not true: the SI Deluxe and SI II software will not run properly if you use a Space Invaders daughterboard. It will continually reset after just a few seconds. To make things even more complicated, not all versions of the Space Invaders daughterboard are the same. According to Midway, boards with part numbers A084-90700-739 B & C are used in upright cabinets only. Boards with part numbers A084-90700-739 D & E can be used in both uprights & cocktail table models. The difference lies in the connectors - Revs B&C don't have the extra inputs for the Player 2 controls.
There's more: If you want to run SI II, you must make sure your daughterboard has the ICs at locations C4 and D4 installed. Most of the time they aren't there. They are needed to make the aux. sound board work. SI cocktail and SI Deluxe cocktail cabinets don't have a second sound board.
The motherboard is the same for all three games, except for the ROMs or EPROMs which contain the game software. There are different versions of the motherboards, but they are functionally identical and can run any version of the game code. Each type of motherboard has a set of soldered in jumpers that determine what type of ROM or EPROM must be used. The schematics for the motherboard show some of the jumper "strappings" for various types of parts, but it is very misleading and very incomplete.
If you skipped the previous section, you really should go back and re-read it.
So you want to know if you can put a Space Invaders Deluxe boardset in your Space Invaders Upright? Yes, you can. The connectors are keyed, and depending on your particular harness it might even plug right in. If it doesn't, then you may have to remove the keying plug at position #9 (counting from right to left) on the rightmost connector to the daughterboard.
So you want to know if you can put a Space Invaders boardset in your Space Invaders Deluxe Upright? Yes, it will work. The connectors should just plug in.