For a used engine with a modest turbo setup and unknown pump calibration, I'd be happy with what the OP got. There's also dyno error, operator skill and calibration to put into the mix as well Thos things can really make things unpredictable. My old '86 has a lot of dyno time. On one dyno it did about 193 hp. A short while later, just 176 hp.Two different types and brands of dynos, two operators and the same truck.
One trick I learned is to make sure the truck, drivetrain as well as engine, is fully warmed up. Cold oil in a rear axle can cost you 10hp at the rear wheels. Gear oil takes a long while to warm up too, so the two or three dyno runs you usually get don't often get the axle fully up to temp. I have a rear axle temp gauge and discovered this, just so you know.
When my Banks kit was put on in '87, Banks advertised 254 hp and 550 lbs-ft at the flywheel. Less about 20 percent, that's around 200 hp at the rear wheels and 450 lbs-ft, if you have an eddy current dyno you can load up to get low end torque. Roughly those numbers show up in vintage publications when the trucks were tested.
I blew a head gasket earlier this year while driving on the freeway, so it's a real danger. The truck is getting studs, of course, and general freshening up. Taking way too long to get it done, though. Valves were in pretty rough shape at 140K miles, but the bores were perfect... barely a thou of taper. Bearings were good too, though there was some cavitation showing on the bearings.
