Get it running on petrol first, ignore the LPG.
LPG like a very good spark so close you plugs up to 27 thou rather than 30, make sure your leads and plugs are like new, avoid resited plugs is you can ie BP6ES not BPR6ES.
The rotor and dizzy capo should be geniune Lucas, not hong kong fuey as the pattern parts often leave a bigger air gap and on LPG this will cause problems.
Timing, don't advance it permentantly, that's my advice, or learn to swap exhaust valves in your sleep.
Fit an advance processor, they have come down to about £100 (less if you know where to shop) and will make up about half the power loss on a single-point or draw through system. A multi point is less economical but looses no power. Put it this way, my LSE can spin it's wheels on LPG, how much more power do you need?