New 331 dyno #'s poor!! Help!!

[Blaster]

The short block was built by a reputable builder who has been in business for quite awhile, but I have not done a compression test yet and I highly doubt compression is low but I will check anyways. I believe he said 10.4 to 1 with my alum. heads. My valve train is exactly the same as it was with the last setup (stock rockers), my timing is at 14 degrees. I also run the same premium fuel I always have. My cam was installed stright up, and my valve train was set up with proper clearances. My exact dyno numbers are 267.7rwhp@5500 and 291.1tq@4000rpm