I have been through this with my son.
A lot depends on your Godson's build, at 13 my lad was quite small, so a Pro-T with Nikko on would have flattened him. We were lucky enough to find a worked up S300 in a modified stock, it had even been custom painted to look like metal panels riveted together, we put a lightweight front focus scope on the front and that got him started.
I then found a superb SM100 carbine in a tiger maple Welham stock, he won a lot of regional shoots with that rifle.
By the time he was 16 he had grown up a lot and was close to 6' tall, so was then shooting a Pro-T with a Leup 20-50 on top (well, he figured I had one, so he should have one too... at my expense).
So I don't think you need to sell up to get him started, as there are plenty of extremely accurate rifles that don't cost a fortune, like the S400, that with a 32 mag scope up top will be more than capable of getting the lad started and which can be traded up at a later date.
"I'm your huckleberry, that's just my game"