Turner do have good reviews and an excellent reputation; I've bought V8 parts from them in the past.
You don't say for which engine but they do standard and performance heads i.e. lightly ported and gas flowed, which is said to improve overall power over a wide torque range and also improve the mpg. No skimming, racy cams or other upgrades, which from what I've read, on 2.25 & 2.5 petrols results in a high revving engine with max torque at high rpm, not good IMHO.
They probably want your old head because older ones are getting rarer and they need a base to work on. Give them a call, Frida (Mrs Turner) is very helpful and knows her stuff.
If LR petrol engines, and improving them, are of interest there's a good debate between Richard Turner and ?Roland of ACR, vendor of a 2.8 petrol and 2.25/2.5 cam, carb and head upgrades (as above). Personally I side with Turner in this argument, and am seriously thinking of getting one of Turner's 'performance' heads for my 2.5 petrol.
https://vidinur.net/2013/05/12/ever...-petrol-engine-acr-turner-others-perspective/