For a situation where the instrument is directly connected to the adapter like here there is no difficulty in fast T1 timing on a MCU. V3 will have btw. fully compliant GPIB electrical specs without 74 series buffers. 48mA drivers are not required for a direct connection scenario as V2 supports. VIH is a bit violated, though not practically meaningful. So far I heard of no device not working after over 6 years and those who did not in early stages I managed to get running with sw updates. This is not a one shot plain textbook GPIB simple thing implementation, it's years of iterations, debug, improvement.