285cc big bore kit includes:

Wiseco piston 78.00/+5.00 10.5:1 (with rings, pin & clips): 

• All Wiseco Pistons are forged from high silicon, low expansion aluminum which offers superior strength, reduced weight, improved heat transfer, and longer life.
• Diamond turned finish from one of the many CNC computer controlled turning centers guarantees you a perfect finish with no size variation. Wiseco pistons can be installed in any of today’s cylinder bore compositions
• Wiseco’s state-of-the-art computerized manufacturing facility is dedicated to supplying both the high-perfomance racer and recreational enthusiast with the finest forged piston available in today’s market place.

HotCams stage 1 camshaft:

• High-performance racing camshafts
• Stage 1 performance camshafts are drop-in cams that are designed to be used with stock valve springs
• In most applications, Stage 1 cams deliver more torque.

Complete top end gasket set:

• High-tech materials provide unmatched reliability and performance
• Rebuild the engine with total confidence as each set is designed for durability and accurate fit
• Oil seals are genuine OEM replacement seals
• Performance sets designed for a piston replacement
• Includes every gasket, O-ring and seal required to rebuild a top end; valve seals, head, base, exhaust, tensioner, and other misc. gaskets and O-rings
• Does not include formed rubber valve cover gasket
• High-compression kits use .012" thick base gaskets to raise compression
• Cost-effective way to raise compression without expensive high-compression pistons or cylinder head work
• All gaskets made in the U.S.A. 

This is a great combination and a big 'bang for the buck' performance increase. 

No re-sleeving required. You will have to have your cylinder bored to fit the larger piston.