I have Indy 500s on my camaro,theyve lasted ok.
I run coopers on my chevelle,which don't seem to wear at all,lol.They do ride rough,but they are solid and a very good price.
These are Mastercrafts,coopers other line,if you don't like having the name "cobra" on yours,which I don't,lol.
If you knew the engine's history it would be better,but yeah,drilling the accessory holes can be sketchy.
For contrast,I sold the 283 out of my 67 chevelle about 4 years ago for 400 dollars.62K original miles on it,didnt smoke,knock,or ping.
Guy needed it for his chevelle resto.Small blocks...
If youre going sniper,youre going to need a throttle extension so you dont kill yourself,or someone else,especially if the car is stick,but out of the box theyre bad enough with an automatic.
That being said,after the throttle extension,you will no longer be able to run a drop base airfilter...
Watch your diameter too.Aftermarket is .5",GM is usually smaller,so your distributor has something to do with it also.
I run the GM melonized gear on my gen6 454,as they specced,but had to have it opened up to .5 to fit my pertronix distributor.