I am looking at a 1970 Buick station wagon and they posted as a 455 engine with 370 hp however has single exhaust is this correct
Yes, that is what the specs say. It is gross HP though.
1970 GS455 Stage1 Race weight 4025 lbs.
TSP 470, 602 HP, 589 TQ
MT headers, Gear Vendors Overdrive
Best E.T. 11.54 Best MPH, 116.06
1998 Riviera SC3800