So I just bought an xj8 sport with only 88,000 for 3,300 and I noticed that I have a small tick in the top of my motor. Should I replace the parts? Or should I swap for the 4.2 supercharged motor in the newer model? If I should swap is that motor gonna be a better swap? What problems would I run into if I did do the swap?

 

You don't give us a whole lot of information to work with. What year, model Jaguar?
Since we don't know if it already a S/C or normal aspirated engine it makes it hard to advise. Assuming it is a N/A you can switch to S/C if COST is not an issue. The electronics on an N/A will not support a S/C engine. It can be done but the cost exceeds the value of the vehicle unless you can personally deal with the programming.

 

Before going any further, remove the cam cover(s) and inspect the secondary timing chain tensioners. If they're the early plastic style tensioners, the primary and secondary timing chains, guides and tensioners must be replaced to avoid catastrophic engine failure.

You don't mention where the vehicle is being operated as swapping engines may also be illegal as well as costly.

 

+1 Timing check.

 

Mine ticks too, I did the tensioners Etc, mechanic told me it's the noise the injectors make.
Drive it.