Dyno question

[Toro67]

I had my car dynoed this weekend and I have some questions:

First, I noticed that the HP and torque (in ft-lbs) cross at around 4100 RPM. Should this cross at 5252 RPM?

Second, this engine was rated at 375HP and 390 ft-lbs from the builder (FWHP). It dynoed at 240 hp and 300 ft-lbs (RWHP). This is a 350 ci, iron heads, 750 cfm carb, mild cam, 32* total advance, 10.2:1 comp, 2.5" exhaust through glass-packs, flowtech shorty headers (1.5" pri and 2.5" coll) , electric fans, 700R4, steel driveshaft, 3.73 gears, 10 bolt, eaton posi. Does this sound right? This was on a mustang dyno.

I know I could advance the timing to 36* and I need a better exhaust, but I still think the 375/390 from the builder is a bit "optimistic".