bucking, bogging out and dying under load or high revs

[gudjeon]

Drive it for a bit. Keep an eye on it. Mine did this for a year before the fuel pump packed it in. It would have been easier if it just packed it in all at once.

[singingcamel]

Sometimes buy just tightening things up will the draw of unwanted air leaks into the fuel system, especially the base of the carb.

[Dietersrover]

You know the old saying, " Timing is everything". I would check the timing make sure the distributor did not move.
I would also check the ignition coil and the wire going to it.