Hello all, this is my first post.

A couple days ago I bought an RX8 with 108k miles for 1500 bucks with low compression. The previous owner took immaculate car of the inside and outside of the car, I have all the maintenance records along with a very detailed history of any mechanical repairs or big projects. It has a Series 2 transmission, brand new clutch installed from the Mazda dealership, full exhaust (minus the cat since he gutted it thinking it was the cause of the tinging).

Unfortunately for me, the car does not have a strong motor.. It has low compression at around 5.3-5.6 kPa at around 255rpms, compression tested at mazda dealership. The motor starts quick and drives, as well as sounds great under 5k rpms but the second it hits it starts tinging off what sounds to be a premature rev limiter and loses most of its power. I can only describe the sound of the tinging as marbles in a can. The previous owner thought it was the cat but after gutting it the problem was still there leading me to believe its internal. I bought this car knowing full well of this issue with hopes of selling my 97 nissan maxima and saving some more money for a rebuild. After calling a few shops and local rotary specialists I am stunned at the prices they are telling me. I know 3-4 grand might not seem like a lot for many members on here but im in my second year of college at a university so money is very tight. I called Kurt Robertson, a local rotary specialist who quoted me at around 4500 for a full rebuild along with an upgraded radiator and clutch(?) unsure why he added those two last items in the pricing especially considering the clutch is already new from the dealership and it never had any history of overheating.

To make a long story short, I am in need of some guidance on what to do to with the motor, is there a link to a comprehensive guide on how to take pull, disassemble, rebuild, and the putting back in of the motor? I have a garage full of tools and various things, which are some specialty tools I might need? I have done suspension work, oil changes, I helped by buddy put in a new motor in his 1999.5 cabrio and got it running that night without breaking anything, as well as assiting in the instillation of a flying Miata turbo kit on a 1999(?).
Is this a project i should even think about doing myself or should i just cry myself to sleep and save every penny i get to rebuild this motor.

Time is a non factor in this since most of this wont be done till the summer, but i need to know what needs to be done.