Welcome. You'll find stacks of discussion about the pros and cons of greys and reds on this site.
A search for "timing gear" (go back further than 180 days to be sure to find it) will give you the good oil
about the issues of fibre vs steel vs alloy etc. Fibre timing gears were also a feature of some reds, and even the steel ones aren't indestructible. The fibre ones tend to fail because they become brittle through lack of proper oiling. They're a weak point, but they're also designed to be, because they're a lot more accessible than the cam or the crank. A failed timing gear won't break anything else, unlike the wreckage a broken crank can create...
Because you're starting with an EJ, I would think the only set-up for grey/red conversion would be the cross-member. (Grey has single mount underneath, Red has two mounts, either side.) 138 to 149 is less than 10% increase, which means in most states you don't need to do anything else for rego. What you might want to do for safety is another issue of course.
The cost and risk associated with the work on a 40 year old head to convert to gas means it's certainly not a popular option. The effect on the (hardly neck-snapping) performance of a grey in a heavier car like an EJ van would be pretty tiresome if you're considering any sort of lengthy trips. If nothing else, at least red motor parts are easier to come by and cheaper, something you could have a long time to ponder in Kickatinalong, waiting for a grey water pump to arrive from the coast...
Hope that's some help. Have a good hunt around the site, and use the Search function. You'll find lots of useful advice and technical knowledge.
cheers
RET