EDNote: Thanks to Sergey Karpukhin for providing the relevant details.

The paragraph in question, quotation 65, (pp.1217-8) is indeed on the same page as quotation 62 (p. 1217) in Chapman’s edition (corrected by J.D. Fleeman, OUP, 1970), both relating to the year 1783 (footnotes in square brackets).

I cannot help mentioning with much regret, that by my own negligence I lost an opportunity of having the history of my family from its founder Thomas Boswell, in 1504, recorded and illustrated by Johnson's pen. Such was his goodness to me, that when I presumed to solicit him for so great a favour, he was pleased to say, "Let me have all the materials you can collect, and I will do it both in Latin and English: then let it be printed, and copies of it be deposited in various places for security and preservation." I can now only do the best I can to make up for this loss, keeping my great Master steadily in view. Family histories, like the imagines majorum [‘statues of our ancestors’] of the ancients, excite to virtue; and I wish that they who really have blood, would be more careful to trace and ascertain its course. Some have affected to laugh at the history of the house of Yvery [written by John, Earl of Egmont]: it would be well if many others would transmit their pedigrees to posterity, with the same accuracy and generous zeal, with which the Noble Lord who compiled that work has honoured and perpetuated his ancestry.

SK