Hi There

Have you any further information , make model engine etc 

Try Precision international , phone or can ask them online during bussiness hours via help / chat with us     that pops up in corner of screen or leave a message. 

can buy online from them , ive brought from them plenty of times .   

Cams & Valve Train & Timing (precisionintl.com)

also worth trying is CBC bearings , BSC bearing service centre,  State wide bearings , chain and drives , sprockets australia . applied industrial technologies .   some of those will have listings for vehicles and engines . some could supply in lengths , sometimes special order as not stocked .

let us know how you go . 

Try this mob 

R M Fowler Ltd - Classic and Vintage cars directory - restoration, dealers and Parts (classiccarwebsite.com)

Home | ChainDrive.co.uk by RM Fowler Ltd - Block, Roller and Timing Chains for Historic Vehicles (chain-drive.co.uk)

Excellent lead , been doing that this week they had a link to Ramsey chain in the US (they make the stuff) and they in turn had distributors around the globe ant the one in Aus is Sprocketsoz  , they`ve got SC405 1/2 inch pitch centre guide on the roll 

There not giving it away but they are good to deal with and they will cut to your length and provide a joiner , so catastrophe averted , thanks to everyone who provided leads