LPG gas and 2 litre Pug/Xantia engines - alloy manifold?

[acreid]

I am looking to convert my Xantia (2 litre, 8 valve Pug engine as used in 306s) to LPG gas.

The easiest method of conversion will not work with the standard plastic manifold - does anyone know if this motor ever came with an alloy or metal inlet manifold? Conversion with plastic inlet manifold tends to lead to exploding inlet manifolds if there is a back fire.

Only other way to convert to LPT is using positive injection, which is much more expensive eg 2000 GBPounds for conversion.

If anyone has done an LPG conversion I would be interested to know how it was done, and whether there have been any problems!