Thanks again John and Steve, much appreciated!
Yes, 500AH on my Geo 530 legs (actually a predecessor called Carmagne 530). Works very well and I got both parts used for less than 150 euros together. Added a mulepack which makes it very comfy to lug around.
I have both the Sirui VA-5 and the Manfrotto MVH500AH. I use the Sirui with my Opticron MM4 60 and find it to be an excellent match for this lightweight travelscope. However, if the wind is stronger (from about 14-15mph onwards) I usually use the Manfrotto head instead. The MVH500AH is, in my opinion, a better performing head; it is more stable in the wind, and smoother (the panning on the VA-5, whilst adequate, is a tad jerky by comparison). But in most situations I choose the compactness and lightness of the Sirui over the optimal performance of the Manfrotto. However, for anything substantially heavier than the MM4 60 I would personally prefer to have the MVH500AH to get the best performance out of the scope in the widest range of conditions (The MM4 77 is not a particularly light scope - 1529g with the SDL zoom). But I remember reading on these forums that someone was successfully using an ATS65 (1405g) with the VA-5, so if you are willing to compromise a little bit on performance, it would probably be a good lightweight solution for the MM4 77.
the plate is attached to the foot of the scope with the 1/4" screw.
I have received the MVH500AH and the Velbon Geo 630 Cf tripod and it seems like a great combo, thanks to all for your input!
Just waiting on delivery of the scope now, my question is:
Does the QR plate supplied with the head simply attach to the scope and I'm good to go or will I need some sort of adaptor?
I also have a nice combo, similar to yours (Velbon GEO 630 carbon tripod + Manfrotto 701 HDV fluid head, the predecessor model) and I like it very much. From 2014 I use a big Nikon Fieldscope ED 82A with it and until now I never felt the need to change anything.