sorry for a double post - but I just noticed your reply - imho keep the vac advance - it only comes in at part throttle, so you never get it at full throttle, it shouldn't hurt detonation.

Very very generally speaking the 'bigger' the cam, the more intial advance you want/need as the motor is less efficient down low, but conversely,. the less total advance you want as it's better up higher. So you need to alter the mech advance mechanism to reduce the total amount of travel. I can't speak for overseas fuel, but generally speaking, for hotter cams, having the mech advance all in by around 2800-3000rpm used to be 'the go' but with more modern fuels (even of similar octane) they seem to be happier with slightly stronger springs to slow the mech advance so it's all in by around 3200-3500rpm.

As a very very very rough guide, I'd suggest you'd want something like 12-14 initial timing, and 32 degrees total (and that's a guess, in all honesty) timing all in by 3500rpm. To find out what total timing to run there is a 'trick' of sorts - and it is this - at the dragstrip, start with 28 degrees, then do a few runs, then 30, then 32, then (if required) 34 and beyond. Basically what you are doing is completely ignoring the ET, (though you still drive it to run as good as possible) and you look purely at the mph. The mph is a good indication of the power (whereas et is indicative of traction, power to weight, gear ratios, powerband, you name it) the motor is producing on average from a couple of thousand rpm shy of and up to and including redline. So basically keep advancing the timing whilst the mph improves, and if it pegs/levels off at say (for arguments sake) 34 degrees - i.e. it is no quicker than at 32, then go back to 32 degrees and you have the 'magic' figure. Then of course you go back and alter the advance mechanism so that you can dial in the right amont of initial advance (i.e. the 12-14 degrees or so) and still hit that 32 total timing at higher rpm.

The other reason I suggest sticking to vac advance, as it'll clean it up more at part throttle, and the bigger the cam, the more it'll 'appreciate' that at part throttle. It can also help slightly crispen up the throttle response, as it takes a split second for the vac advance to spring back to 0 when you slam the throttle, and so it gets a fraction of residual advance just as you do that (and let's not forget that's the one time when fuel metering is taking a split second to respond to increased airflow - of course there is the acc pump to help, but this is a little bit extra help on top, and for free no less.