The higher ratio gives more lift without changing duration.
Since you will be swapping the cam anyway, I would pass on the high ratio rocker and do the lift on the cam instead. The added leverage will be trying harder to pull the studs out of the head. If you pick the right cam you won't need the fast ratio rocker.
Since you have stock heads, there are a few catches...
Stock rocker arms are rail style. You will need rail style (flanges on the sides of the roller tip to keep the rocker from rotating off the valve stem tip).
Or... Switch to guideplates, which will require removing the heads and having them machined for threaded in studs and the studs will now clamp the guideplates in place which will now hold your new hardened pushrods. That's a lot of new parts and machine work. You had a budget of $150 for this?
And all of the above options will now require you to set the lifter preload as it will no longer be a bolt down and go like they are now.
When you do the cam swap, if the old parts (pushrods and rockers) look good, reuse them. But if they have wear, the roller rockers can price in close to what a bunch of stock replacments would. Then you can get a little nicer rocker for not much more money. With a fairly stock engine and only an RV cam you won't be stressing parts bad, you shouldn't need any high end billit ultralight parts. But you will probably going to have to spend a few extra bucks for the rail style rockers to avoid spending even more on other parts. Even then I would just do the 1.6 ratio.
