I'm assuming 'Old-school' refers to the 80s-90s version(there's an 'old-school' that's older still). The 80s-90s version had O-ring rubberbands and metal pinned joints and were 3 3/4" tall. Modern GI Joes are 1/18, meaning they hover around 4" tall(with 'heroic' scaled height of 6 feet), which is the same basic height as the SHODO Kamen Riders.

The SHODO Dragon Ball run was at first smaller, but I think that they've been up-scaled to be 1/18 as well.

Here's ShodoVS Rider 1 from Part 1 with an assortment of figures in similar scales. Top row is other Rider lines and Samurai Red for reference. Bottom row is other toy lines. That is Neo Shodo Goku next to Rider 1. Seems Bandai included the hair in his measurements, so his scale is still way off.

http://www.tokunation.com/attachment...1&d=1450018992

I had thought these would be closer in size to the Kiwami Tamashiis, but I'm remembering now that those figures always were a little taller than the standard 3.75" scale.

The thing about them is that they're not 3.75", I think only ReAction still uses that as a 'scale' anymore('size class' would be more accurate, as the figures were sized to fit particular packaging standards rather than conforming to a scale). 1/18 would be more accurate, with that being if you consider the character to be about 6 feet tall in his suit as the figures are about 4" tall.