Gear Ratios as recommended by Nigel Lingwood as a good starting point

 

Hewland Mk8/9	Avon ACB9				Avon ACB10
9:31CWP	1st	2nd	3rd	4th	1st	2nd	3rd	4th
Anglesey	15/36	19/32	22/30	24/28	15/36	19/31	22/29	24/27
		(20/32)	21/29	23/27	15/35	20/32	(22/28)
		(20/31)	(22/29)	(24/27)
Brands Indy	14/36	19/32	22/29	24/28	15/36	19/31	22/28	24/27
				(24/27)		20/32
Brands GP	14/36	18/32	22/29	24/27	15/36	19/33	22/28	24/26
						19/32	23/29	25/27
Cadwell Full	14/36	19/32	22/30	24/28	15/36	19/31	22/29	24/27
			(22/29)	23/27		20/32	(22/28)
Castle Combe	14/36	19/32	22/30	24/27	15/36	19/31	22/29	24/26
			21/29			20/32		25/27
Croft	15/36	19/32	22/29	24/27	15/35	19/31	22/28	24/26
				(24/28)	(15/36)	20/32	23/29	25/27
Donnington	14/36	19/32	22/30	24/27	15/36	19/31	22/29	24/26
			21/29	(24/28)		20/32		25/27
Donnington GP	17/34	20/32	22/30	24/27	17/33	20/31	22/29	24/26
				(24/28)	(17/34)			25/27
Kirkistown	17/34	20/30	22/28	24/27	17/33	21/30	23/28	24/26
		20/31	22/29		(17/34)	20/30	22/28	25/27
							23/29
Knockhill	15/36	18/32	20/31	23/28	15/35	19/33	20/30	23/27
					(15/36)	19/32		24/28
Lydden	14/36	18/32	20/30	23/28	15/36	19/33	21/30	23/27
		(18/34)	(20/31)			19/32	(20/30)	24/28
Mallory	15/36	19/32	22/29	24/27	15/35	19/31	22/28	24/26
				24/28	(15/36)	20/32	23/29	25/27
Mondello	15/36	17/34	20/30	22/28	15/35	17/33	21/30	23/28
				22/29	(15/36)	(18/34)
Oulton Fosters	14/36	18/32	22/30	23/28	15/36	19/33	22/29	23/27
			21/29	(24/28)		19/32		24/28
Oulton Full	14/36	19/32	22/29	24/28	15/36	19/31	22/28	24/27
				23/27		20/32	23/29
				(24/27)
Pembrey	15/36	19/32	22/30	24/28	15/35	19/31	22/29	24/27
			21/29	23/27	(15/36)	20/32
Silverstone Club	14/36	20/32	22/29	24/27	15/36	20/31	22/28	24/26
							23/29	25/27
Snetterton	14/36	19/32	22/29	25/27	15/35	19/31	22/28	25/26
				24/26	(15/36)	20/32	23/29
Thruxton	14/36	19/32	22/29	25/27	15/36	19/31	22/28	25/26
				24/26		20/32

Close alternatives are shown below.
Usable alternatives are shown in brackets.