I would'nt go quite that big with your valve, I would go with a 1.880" intake and stay with the exhaust size you have. The offset valve guide trick will still require welding up on the backside of both ports just under the deck to the valve guide plane. As far as filling up the area around the valve guide, unless you are trying to increase your torque at idle you will not see a big increase. Remember this, on a K series Kohler, most of the flow that counts is from the centerline of the flange bolt holes and up, I too have seen the epoxied motors and they do run well, but when you remove that much mass from the block then your block is not as rigid, the deck thickness on the K series varies greatly across the entire surface, and if the valve seats cannot be supported properly then you will just have heartache after heartache. If yu want to reshape the port then I highly recommend either cast welding or braze welding on top of the flange clear to the deck, build it up to the same heaght as the deck from the flange back through the center section of the port. This will allow you to reshape it correctly while remaining strong enough to hold the carb. and intake manifold. The crank issue is simple, Kohler cranks are made of cast iron, they will hold up about 35 hp/ 30 -35ft. lbs, much more than that and it will snap! I built one for a guy several years back that snapped between the counterweight and the cam gear on the inside, this happened while I was tuning the carb. face to face with it. If you do decide to start over, then stay with the K series motor and do not mess with the magnum blocks (M16). I would stay with the valves you have, get the newer piston from Vogel manufacturing, you will have to change rod length though. Keep your cam lift around 0.533" stay with the flywheel you have, don't use the offset guides, if you are going to move the valves, offset bore the guides to a bigger guide, and use a guide liner. Then it is not such a pain to have the guides changed when they go bad, but you will have to cast weld the back side of both ports if you move the valves very much. You started on the right path, just stay the path and you will do fine!!