converter slippage

You're gonna need less gear. 7200 is plus 16% rpm(over 6200). and Plus 16% rpm should be plus 16% mph; so 7200 is good for 120mph. Ima thinking you will be out of rpm before you are out of track!
Stated another way; 103 @6200 is 103/(6200x1000)=16.613 mph per thousand rpm. So 16.613x(7200/1000)=119.613mph

4.30s would get you;4.56/4.3=1.0605 more mph @7200 or about 127mph
4.10s would get you;4.56/4.10=1.1122 more mph@7200 or about 133mph

trapping at 7200,suggests a power-peak at/or around 6800;That's a heckof an engine!