Hi, I've recommended some books on the general topic of Portuguese before. The one from Subrahmanyam you've mentioned is very well thought of

Others include (copied from elsewhere, so recommendations might not match 100%):

• Portuguese Seaborne Empire 1415-1825 (1969) by C.R. Boxer. Boxer is till this day the accepted authority and this book is still the reference book for the Portuguese empire from it's beginnings of expansion to the breakaway of Brazil.
• Prince Henry the Navigator: A life (2000) by Peter E. Russel. The ultimate biography of Infante Henrique in English, who was one of the key people in kickstarting the Age of Discoveries which lead to his elevation to mythical status during the 19th century. This book tries to reveal the 'real' Henrique and goes less into the details of 'his' discoveries (conducted by his authorization by other people) and more into his own life, motivations and decisions.
• Foundations of the Portuguese Empire 1415-1580 (1977) by Diffie and Winius. Detailed book detailing the beginning and peak of the Portuguese Empire in the 15th and 16th century. Accent on the events, battles and general military and political developments. Good also for general review of ships, navigation methods, weapons and equipment.
• Portuguese in Asia: 1500-1700 (2012) by Subrahmanyam S. Accent is on the economy and politics of the Portuguese presence in Asia. It is full of data and statistics about trade, shipping, earnings, costs and the general way the Portuguese presence in Asia was set up. Also gives slightly more information about the Asian surroundings (but the focus is still on the Portuguese).
• The Portuguese in India by M. N. Pearson. Focuses in entirery on Portugal on Indian subcontinent and their organization and administration.
• A History of Portugal and the Portuguese Empire: From Beginnings to 1807 Volume I and Volume II (2009) by Disney A.R. A great overview as well as introductory reading to Portuguese history. You can easily jump to chapters one is interested about. Volume I is chronological history of the mostly mainland Portugal, while Volume II goes into greater details about their colonial holdings.
• Portuguese Sea Battles - Volume I - The First World Sea Power 1139-1521 by Saturnino Monteiro
• The Christian Century in Japan, 1549-1650 by C.R.Boxer on archive.org. Chronicles the work of Portugese and Jesuits in japan until seventeenth century and closing of Japan.
• The Cambridge History of China, Volume 8, Chapter 7: Relations with Maritime Europeans 1514-1662 - chapter dealing with early Sino-Portuguese contacts
• Merchants and Rulers in Gujarat: The Response to the Portuguese in the Sixteenth Century by Paerson. More insight into Gujarati society and their interactions with the Portuguese upon their arrival. Gujarati were the merchants of the Indian ocean, whose trade networks spanned continents. Full free Google book.
• Decay or defeat ? : an inquiry into the Portuguese decline in Asia 1580-1645 by Ernst van Veen -doctoral thesis about the causes of decline of Portugese empire. Mostly about shipping and economy, full of data and comaprison with VOC