It will not be cheap
For the eninge and all the bits like turbo, loom, exhaust, fuel pump, airbox, ecu, dash conversion it will cost more than £2K to do with garege fees etc
so
There are plenty on second hand Octavia RS on about 2002 for £2K on the Bay just buy one of them and enjoy using it. I got one. It handles good, ok on gas mpg and hard wearing, fast, easy to remap to about 205bhp from 180.