Hello Auriel,
Burstner Caravans will almost certainly have used Truma Heaters, and as such virtually all spare parts are available from or through most caravan dealers, However I do not know what ovens will have been used. Double check the gas pressure required, as at that time the continental standard was 50mB which was different to the UK 28mB Butane/37mB Propane.
Clives advice is paramount as some insurance companies will refuse payouts if gas work has not been done by a competent fitter.