The Holley is big and heavy............. but it works. I agree the look of the Trick Flows isn't high on my list, you could fry pancakes on all of them but the R.
Haitham- You will not loose compression with a cam swap. The 274 does have more duration which does move the power ban up higher, that cam should make good power with the combo you have properly tuned with the cam installed correctly.
Maybe your rockers/valves are too tight which holds the valves and that will cause it to loose a lot of power, same goes if the valves are too loose....that adjustment is very important.
If you go up to Crane Cams website they have a lot of Adobe .pdf files that shjow you how to install and adjust rockers, cams etc..
www.cranecams.com
Just a thought.