Flex---
While every shotgun is different and you never know what will function in a given gun until you try, that particular load should give good results for 3-Gun matches.
I like the smaller shot because it tends to pattern better, less flyers, thus I get more lead on big poppers. I don't go to a different shot size for long targets I use a tighter choke. The smaller shot also has a denser pattern for the moving or stationary clays, no big holes in the pattern mean less misses.
If the steel is in tight, 10 to 18 yards, or there are a lot of clays I will use an improved cylinder choke and go for top speed. If the steel is past 18 yards and I'm shooting on the move I use a modified choke. Anything farther out, or if I'm shooting from a supported position I may go to a full choke, but this is rare. For slugs I use a modified choke.
The best advice I can give is to keep the gun simple and quick and to find a reliable load and stay with it. Spend $30 and bust 200 rounds of the Federal through your new toy, expect 100% reliability and see if getting it dirty causes it to quit.
Good luck......