Criterion Pre-fit barrels

In the back of the gun cabinet in the projects dept lies a beaut BSA Model E. I acquired some nice bits for it (a new bolt stop etc) but have never taken it to a conclusion as the barrel is like a sewer pipe.

I saw that Gunworks has some of these for sale, the P14 ones are $570 which is OKish. However before I go down that rabbithole some questions . . . .

Do P14's typically shoot badly if the bore is dark and pitted ?? (I've had good luck with a Mauser that looked bad but shot OK - my Model E is in pieces otherwise I'd shoot it and find out myself)

How much gunsmithing work is required to fit a Criterion pre-fit?

Have you shot it yet ?

It doesn't matter what the bore looks like, or anything else for that matter,

The only thing that counts is how it shoots, whether it has a 100 year old barrel or brand new one :)

I'd echo what Greg says. Can't say I've had much time with BSA P14's but I've shot a lot of pitted barrel rifles. Some shot rubbish others- like my pre64 Mod70 took a while to find a good load but shoots 1moa.
Start with flat base bullets- they tend to shoot better from worn barrels in my experience.