You must have the bonus topbox light bar to use SP944, SP949, or SP1289....SP1289 was the newest program.
According to their respective PSR's in the NLG File System, these are all Type 25 SP chips, and also require SET058 to enable the bill validator.
Unfortunately, you are not a Contributing Member and don't have access to the PSR sheets.
I cannot find anything that says these SP chips would require a 16Mhz MPU - they all use 10Mhz MPU's.
TYPE 25 Special S-Plus: When a specific combination is hit with max coins, the game pays varying coin amounts randomly, accompanied with special lighting and sound effects.