67 383 Dart

Did the 67 Dart have the HP heads with the 1.74 exhaust valve or just the std 915 with 1.60 exhaust valve. The reason I ask is I have a 67 Dart coming to me and It has no power, has 6 - 7 in vacuum at idle I turned up the timing and made no difference. the guy claims after a engine rebuild some 10 years ago it never made any power and it just sits in the garage. I was thinking maybe the guy who rebuilt it put 906 heads on it and kept the 915's or and has the cam timing off. It has a ruff idle but you can floor it and it just drives off wont even spin the tires.

or did they have 516 heads, I wasn't thinking about 915 were 440 only?