more power from vt903

i was wondering if anyone could help me out?
i am restoring an old cab over kenworth vt903@350hp was 15spd direct on torsion bar. replaced gearbox with 18spd and rear end with air bag and 46 160 diffs with 4.11 ratio. what i need help with is finding someone who could give me some information on getting more power out of the 903?
i have thought about repower with n14 but the 903 had full out of chassis rebuild 10000k ago, and the truck is really only just a toy (might do harvest work one day, but most likely never leave the shed)
any info would be a big help
thanks

How much do you want to spend? VT903's in industrial applications had 2 big after coolers, similar to the old 350/400 aftercoolers, and put out 500 hp. LP gas gets them going to. Mind a standard VT350 bob tail is like a sports car. They are a great motor.

I had a 903t in a Louisville and it was set at 450hp at 2800 rpm. It was over fueled to hell and only did between 3.75 and 4 mpg. And with 3.7s, 13 over and 2800 was very quick. Do not suggest this as a solution with fuel at current prices.