Erratic Timing
Sketched the '72 maximum timing onto the '68, and also marked your 1* at 1100 rpm.
Based on what you've posted, if you can get 5* at 800, that would be pretty good. Then see how it drives.
If it has some cam in it, it may not like 0* or even 5* at 600 rpm.
If it is some cam, probably will like an initial more like a pre-smog 273 4bbl (or maybe a police pursuit 318 4bbl using a 340ish cam, I've not seen those timing curves)
That does suggest its not too radical. It still might like a curve with a little more advance in the begining. Funny thing is that electronic ignition distributor's curve may already do that for you!
Sketched the '72 maximum timing onto the '68, and also marked your 1* at 1100 rpm.
Based on what you've posted, if you can get 5* at 800, that would be pretty good. Then see how it drives.
If it has some cam in it, it may not like 0* or even 5* at 600 rpm.
If it is some cam, probably will like an initial more like a pre-smog 273 4bbl (or maybe a police pursuit 318 4bbl using a 340ish cam, I've not seen those timing curves)