You can get Hemi 265's on ebay.com.au for next to nothing.
here is a list of places to get them plus parts:
www.moparmarket.com.au
www.pentastarparts.com.au
www.hemiperformance.com.au
www.valiantspares.com.au
www.ebay.com.au
You will need a new K-member possibly, new extractors/headers which...