IMO, a custom bent 2-1/4 MANDREL bent dual exhaust set up would be well. It will be a bit pricey over a regular bent pipe, but well worth it. Bring your choice of mufflers to the shop and drive away happy.:D
Well put Rumble. The 2 1/4 set up isn't too big for the 273 and later down the road if you want to upsize to a bigger engine you may not need to change exhaust. A quality 2 1/4" set up would make any mild small block happy. Does your trans cross member only have one bend for exhaust? You can modify yours. Use search . There are quite a few threads here about that. 340 manifolds are a bit spendy to find but they have a large outlet and aren't as restrictive as the 273 manifolds. tmm