Aha - that all makes sense
As you can probably tell, I'm thinking about the next project again - despite it being slightly delayed thanks to Mr Tax Man. I was pondering today whether it's a better idea to build the 428 with the injection throttle bodies on initially, or build it with a carb on to get it run in; largely because I know the break-in procedure for the cam is "Start the car, get it to ~2000rpm +/- 500rpm and run for 20 minutes without stopping. Stopping and re-starting may cause damage to the cam" - which sounds like a fairly tough challenge if starting with zero map! On the other hand you can bung a carb on with 'roughly' the right jetting and a distributor with 'about' the right initial timing and you're good to go, at least for the cam break in.
Mine took a fair bit of ssiping about to get it to run on carbs, TBH, (albeit twin DCOEs so a bit more adjustment needed) and 50k later it is clear that it did the cams no harm, as they are still as-new.
If you have a carb and all the bits and it's easy to bolt on it might be good for peace of mind, but I wouldn't go to any special trouble. Once an engine is running it's not that hard to keep it running IME, unless it develops a catastrophic fuel or coolant leak.

It's cranking it figuring out why it won't start that sometimes takes a while.

Last recalcitrant megasquirt install I was called in on (Lancia Beta Monte Carlo

) it was due to the intake cam timing being about 90 degrees out.
I have a spare Facet Red Top if you do go down the route of lashing up a temporary carb fuel system, although gravity feed from a lawn mower tank will probably do the job just as well.