I would say forget the stroker kit. Save your money. I also agree that sometimes the compression was less than advertised if you tear it down and measure. The old 390 I took out of my car was nothing special and ran just fine on mostly pump 93 with a little AV mixed in for good measure, 38° timing. It was around 9.3:1 I figured, when I tore it down. It was just .030" over with a windage tray, a mild hydraulic flat tappet(Wolverine 224/234 @ .050" .536"/.562" on 110/105), factory C6AE-R's with light hand port, Edelbrock performer RPM, ancient 4777 650. Headers, of course and a 4.33 gear. Judging from trap speed, it was making an honest ~400hp or so. Felt strong for what it was.
Falcon- If you are not recommending the O.P. use pump 93, what are you suggesting? I see no reason it won't run OK on pump gas. I have run it in mine with no ill effects and have been using it in my daily for 3+yrs. My daily, way off topic, is a 4.6 Crown Vic. I use Shell fuel exclusively. When I have pulled the plugs a few times, they are always clean and the tops of the pistons that I can see are also very clean. This is efi, though and I run a 4.10 gear. Maybe that helps, maybe not.