They normally just have a piece of strip steel that pushes the Off button when the bow gets to the lowest position.
I've only just noticed that the bow on yours swivels which would complicate the usual arrangement.
Mine is a swivel bow and had the 'usual' arrangement for the switch originally.
Nice job! I have a box full of those things - posh Telemechanique ones.
Is that a hydraulic damper fitted to the front?
Mine doesn't have that if so, and that's where the switch lives.
No, mine is badged as a SIP, but with the exception of the cast bed and hydro ram it looks the same, just a different colour.
Mine does have the same vice, but it was bolted to the base, which was (crap and) folded sheet.