Question on building BOSOZ.

Hello All, I am building the BOSOZ and I will be using it single ended and if I read the instructions correctly I should replace R3,4,5 and 6 with 40ma constant current sources to lower the noise in single ended operation.

My questions are: Am I reading the instructions correctly and is the assumption above correct or can I just use the R's as shown on the plan and not worry about it?

My seond question is where do I buy constant current sources or is there a formula for constructing same?

Thanks for any information.

Tony D.