1971 F-250 428 FE Surge!

[Chico]

G'day all!
Hoping someone can help.
Could be a simple answer.
Noticed in the last 2 weeks when I'm cruising around 40-50 mph I'm feeling a slight surging/hesitation. Gas pedal held steady and just seems to happen a bit more noticeably when warmed up? Timing is fine and idles ok.
Has a MSD distributor and a QFT 750 carb.

Any ideas? Air/fuel mix? Fuel pump?
Plugs?
What's a good place to start?
Please be kind I'm figuring all this out on my own. Not a whole lot of guys in my town with FEs