The Xe284H-10 is a better cam for your purpose. As far as being a good match to your combo stop
listening to people who no nothing about cams or ported 305 heads.
Don't ask people on the internet how much power you will make. They don;t know.
That what they make dynos and race tracks for.
The 292H magnum is not a bad cam. but....Id rather see you use a better solid lifter cam if you want
to go that big on the cam. It will work a lot better. Don;t be intimidated by street solid lifter cams.
They are not hard ro deal with at all.
Your friend is not the only guy with a cam for sale. You can buy a new cam for $150.
In a hyd the XE284H-10 would have been a good choice.
Yes your ported big valve 305 heads will work very well with it . If you did a decent job on porting them they actually flow pretty good. The only way to know how thye turned out os to run it down the track, stick it on a dyno or flow test the cylinder heads.
You are on your way to a good combo for the street for your vette. Don;t fuggg it all up now.
A Isky Z-27 cam would work very well. #201027. Another cam I like even better for this combo is the Lunati 401A3LUN cam. A nice street solid cam that will run nicer than the comp 292H. You will like it better overall.
good with your ported heads, good wiht the 3/4 shorty headers good with the 3000 stall and 4.11's.
The comp 292H needs a higher stall converter. 3500++.
Thats what I would do if not the Comp XE284H-10 cam. The comp Xe284H-10 cam is the biggest I would go with the 3000 stall converter.
Grind number 01-UF15-UF16-12 part number 401A3LUN
272-282 238-248 @.050" .485" .503" 112LSA .020" lash. use a lunati 73943 valve spring.
(the comp 981's will work with this cam if shimed correctly. Ya this matters.)
These "NEW" Lunati cams are UD Harold/Ultradyne Cam designs. Known for being really good cams.
This is a sweet street cam for your Vette.
Based on your picture you have dished pistons. Install the 305 Heads with a felpro 1094 steel shim head gasket to get the compression ratio right. Install clean and dry on a clean dry block surface. ya this matters.