No, they only released 308 in Brougham at the start of HT and of course only with Powerglide. Every other V8 model HT (except GTS350) was 253 if you wanted a manual or 307 if you wanted an auto. It wasn’t until all 307 and auto were allocated to production that 253 auto or 308 were available anywhere (except 308 auto was always in Brougham).
The remaining 307 and associated Powerglide left at the start of HT were unused from HK. Remember GMH’s final order for these would have been prior to July 1968 when Monaro and Brougham hadn’t even gone on sale yet. All of those HT 307 engines were built before the end of 1968 year model engine production which finished in July 1968. Any V8 SBC engine built after July 1968 was a 1969 engine and looked like the second type 327 and HT350 engines. What happened was a combination of HK Brougham not selling as predicted and GMH having to add maybe 500 more GTS327 to the schedule than originally intended (so the GTS327 qualified to ARDC rules to race at Bathurst 1968) which meant production had to be reduced to accommodate those extra 327’s, the most likely bring reduction in production of what wasn’t selling so well were Brougham and Monaro. We know predictions for Monaro sales were wrong as everyone wanted GTS’s, so June and July 1968 production Monaro were still being sold as new cars in 1969.

No 308 4sp manual in HT you claim.