I have one and have the 260hp small blocks. I dont think you need big blocks (you would probably only pick up 4-7 mph at top) but if you can get the 300 hp mercs that would be good. If newer I think they were also fitted with the 6.2's at 320hp (I think). A very comfortable day boat for its size with decent performance. Pretty easy to trailer and launch etc.

I believe the 28SS is only available with a single big block or twin small blocks, not twin big blocks.

Did they even offer twin BB's in the 280 SS? I've seen them in the 330 SS but can't recall a twin 280 SS with big blocks. Twin 350's would be perfect in a 280. Have a friend with a 330 SS with twin 350 MAG MPI's and Bravo III's and it does quite well.

I think your right. I just confirmed The one I had in mind is a 330. Sorry for the confusion.

Cobalt quality is second to none. I've never been in a 29 but have lots of hours on a 27 and it road really well in all conditions.