273 hi po engine

It is a good little engine. Most folks here prefer the larger LA series engine, the hp/dollar ratio is better with more cubic inches. The factory spec Hi-Po 273 is rated at 235 HP which is pretty good for the day. I built mine because it is original to a low-mileage all original car. For a real go-fast, you are going to want a 318/340/360 LA build. There are a few of us on the board who have built the 273 with success. It boils down to what you want the car to be. Search the small block tech section of the board and there will be reams of information on your question.
Best of luck with your decision, Rat