Getaway uses 4 services switch and as far as I know High Speed uses only 3 - so there is a difference right away that would not make it a simple plug and play (even if it was you would lose some functionality).
Also the connectors are did (I think) - the Getaway uses a flat Molex connector that plugs into a board near the coin door vs. High Speed probably feeds back to the main board in the back box.
If they both used the same system processor, then yes, but since they don't - not likely without changing the connectors (and still missing a service button).