For starters, the cost of the throttle cable, harness, clutch lines, and whatever else you need will not even come close to the cost of a right hand drive conversion. You can get all the parts you need except the harness from just about any junkyard you go to. Max cost would be about $300-400. Converting a car to right hand drive is a major undertaking. The entire front of your car would have to be taken apart and reassembled. Anyone you could trust to do the job would charge an arm and a leg to do it. I'm talking at least a couple thousand dollars once all the labor is factored in. And that's a conservative estimate.

The firewall is a MAJOR torsional support for a vehicle (keeps it from twisting). While removed, if the car twists at all you will have major problems in the future. The least that could happen is you end up with a car that constantly squeaks and rattles. Worst case, you alter your suspension geometry.

If you really want to do this, you need to decide if it's worth the cost. If you find a good body man with the right equipment, the negative outcomes become much less likely. Buy you have to realize that anyone that good that has that much money for the equipment has that much money for a reason. Personally, I wouldn't recommend it. But, if it's really worth it to you to be different, to each his own.