I'm thinking to get one of these to improve my safety after getting a boot the other night when I got careless. So would these specs be ok (cheapest model?
240V in and out, power rating 300 VA 1.25 Amps. If that is not adequate what do I need?
Any advice on this would be appreciated

http://www.flanagan.com.au/isolation.htm.

I would recommend something a bit beefier than 1.25 amps. As a rule, always double the capacity that you believe you will need to allow for headroom and reliability.

As for safety around high voltages, there is no real substitute for due care. Isolation transformers and RCDs do provide some protection but only under certain circumstances.

Some things to do are:-

1. Keep workshop and especially the workbench clear of clutter and unused tools and parts.
2. Use thick carpet or a rubber mat on the floor as an extra layer of insulation.
3. Wear shoes when working on radios.
4. Secure the chassis in some way, whether it be a suitable vice or other clamping method, to keep it still.
5. It's not always possible to successfully repair a radio without operating on it live. When the power is on keep one hand behind your back or in your pocket so there's no path for current to follow through your heart.
6. Equip your workbench with an isolation transformer or RCD. The properties of an isolation transformer will render an RCD's safety function inoperable so one or the other is adequate.
7. Don't let anything distract you when working live and only work live when absolutely necessary (to take measurements, etc).

One other thing I'd recommend based on an experience I had today - when playing old radios always remain close by them. An AWA Radiolette from 1947 that I have used in my office at work since the start of the year died this afternoon due to its power transformer shorting out and coming up to boiling point. It was a case of good luck that I was at my desk at the time when the music from 2CH suddenly stopped and the sizzling noise began.

I will describe a refit I have planned for this radio at a later time however at the moment it is an example that one can never take too much care with vintage electrical appliances, or one's self.

Thanks Brad, I have printed that advice out and pinned it to the wall of my work bench.
cheers