The trick with the Wellbrook loop is that the loop isn't tuned. Tuned
loops make sense if your radio itself has poor filtering, but anyone
who forked out money for a Wellbrook already has a decent radio. You
have to admit the Wellbrook marketing is clever. They don't have to
compete with Kiwa, Quantum, etc.

In a good amplifier, you set (or blow) the noise figure at the input
stage. [You can do worse of course if you aren't careful.] Thus
starting with a source follower means you are inserting a noise source
right that the front end. Since noise is "input referred", starting
with a source follower (i.e. no gain) means that you don't have the
gain of the transistor to reduce the noise. Thus you should start with
a gain stage. Now this is where I don't know what Wellbrook does. For
low noise, you want a single ended input stage (one less elemen to
contribute to the noise). For the loop to work, it has to float about
ground as you don't want the antenna to be the loop relative to ground,
i.e. you want the loop to be the antenna. Thus Wellbrook puts in a
differential to single ended converter, aka the transformer. Now what I
don't know is the turns ratio of the transformer. Are they picking the
turns ratio fo impedance matching? Is the goal voltage gain?

I don't think the Wellbrook is complicated in terms of the number of
components, but it requires good planning to make a low noise amp that
works with the loop.

You may want to investigate North Hills transformers. They often show
up at swap meets or on ebay. They are very wide band.