I have the same vibration at 2600rpm which is between 60-80kmph also I think it is coming from my redline sports air filter assembly

going by that it sounds like the idle mixture screw has vibrated itself in a bit?
I had the same problem on my weber 38 DGAS carb, I put an O-ring on the screw to stop vibrations altering the setting

I am pretty happy with the idle / slow speed circuit and I am almost ready to start fiddling with the main fuel circuit to see if I can get more out of it, but a broken engine mount has delayed my testing time this week
will get stuck into it and let you know each detail of the tests soon hopefully

I had a new rear tyre put on my commodore last year, paid for a balance and alignment and when I picked it up I noticed a strange vibration above 90kmph, had a look at the new tyre and it was a directional tyre that was correctly fitted BACKWARDS! silly buggas

sounds like electrical problem to me if it won't idle and runs rough at higher rpm.
I would first check easy things like ignition timing and points gap, if they seem normal try looking at the plugs and high tension leads if all that seems normal it could be a vacuum leak around the carby base or intake manifold to head ports.
my guess is points have gone bad

My X-Trail has JETT 05 on the plates, my sons name and the year he was born, kind of an early 18th birthday pressie for him.....really early
I want some plates for the datto something like EL DATTO because the "EL" is actually 73 upside down, heh heh clever! or TIMEBOMB BUZZBOCKS or something catchy and cool

wholly twisting chassis rails batman did they cost you $105.98?

also before you do anything rash have a look on the ebay.com site under a seller named alfa1750 he sells heaps of jets, carbies and almost any other bit for induction set ups

I think maddat.com.au specialise in that conversion

Oh yeah man I have been there!
I have an A15 with a 240 degree cam competition valve springs, datrats dizzy, big ports, extractors and 2 1/2" exhaust and a weber 38/38 DGAS downdraught carburettor. I had a problem where it would hit about 5500rpm and start coughing and spluttering pretty badly and wouldn't rev any more, after a couple of weeks or testing new parts, trying different jets, spark plug gaps and timing settings it all came down to two things.
1) I fitted a new fuel filter and when I disconnected the filter-to-pump line I noticed quite alot of air bubbles escaping from the filter outlet before any fuel came pouring out. I think I had air cavitating in my fuel pump causing incosistent flow into the carburettor bowl.
2) I put a new set of NGKBP5ES plugs in and left them gapped at .033" which is the stock gap, previously i had tried running .044" gap because thats what the datrats dizzys are capable of