princepilot
If you are seriously interested in instructing only, why don't you consider instructing on the the new generation of 3 axis microlights? They are in essence comparable to your C150's and Tomahawks and many are now far better equipped than the ancient aircraft mentioned. The plus is you only need a PPL and the 200 hours plus doing an FIC (microlights). It is a real growth area and the pay is good (£50 plus an hour) compared with the peanuts you will get as a group A aircraft instructor. If you want to later get the CPL/IR you can at least get the money to pay for it by working in instruction. As far as a return on the training investment the microlight (VLF) route shows a far better return!