Adding Weber tremolo to an RD-50?

Hi All,
I have just taken delivery of a near mint RD-50, 112. I've been after one of these for years and (of course) paid through the nose to get my hands on it. Water under the bridge etc... However I'm dead keen to add tremolo to it (or 'vibrato' in Fender language). I see that Weber sell a little board at https://taweber.powweb.com/store/modkits .htm#vibe that looks the trick. Has anyone used one of these successfully, either on the RD-50 or on another amp? I'm thinking it could be applied to the output tube bias which I assume is the 30VDC supply from the +ve side of the bridge rectifier. Any thoughts would be much appreciated. I know I could buy a pedal but it's just more clutter. I bought this amp partly because my 65/210 is about to hit the bench for a rebuild. I'm an electronics nitwit so I'll be taking my time and wanted a 2nd amp to use. Thus far the RD-50 seems impressive although the lack of tremolo is disconcerting after using the old 65. Nice to carry though!