valve inserts

i have just taken the cyl head off of my s1 for a de-coke, and of course one exhust valve seat is cracked, now ime thinking if i hann"t botherd with the decoke i would have driven on but now that i know that the crack is there it will nag more than the misses, it seems to be fairly easy to replace the insert if i make up a tool to pull it in, has anyone out there done one? and wears the best place to buy sutch a thing?
Thanks

not something i have ever done
probally best to take the head to your ocal engine rebuilders and get them to change it for you
it isnt gonna cost a lot and would be best to have it done right or you may end up with more trouble in the long run

Dunsfold have some orginal S1 valve seats in stock

only send the block to an engine builder if you don't like having money in your wallet

done it loads of times on bikes.mig weld around the inside of the old seat which shrinks them allowing them to fall out.warm the head gently with a blowtorch having put the new seat in the freezer the night before.it should just drop into place but might need a tap with a brass drift.

putting the head on the stove while the seat is in the fridge helps avoid having to drift it in

thanks for replies, would not have thought of mig welding the insert, cant warm the head the ex valves are in the block, meens engine out to have profesionly replaced, i have found the drawing for the land rover tool so i am going to make one and give it a go , i will try dunsfold for the part thanks